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Rout, S.; Sankar Bhattacharya, S.; Horodecki, P.
Randomness-free Detection of Non-projective Measurements: Qubits & beyond Working paper
2024.
Resumen | Enlaces | BibTeX | Etiquetas: UAB
@workingpaper{nokey,
title = {Randomness-free Detection of Non-projective Measurements: Qubits & beyond},
author = {Rout, S. and Sankar Bhattacharya, S. and Horodecki, P.},
url = {https://doi.org/10.48550/arXiv.2412.00213},
doi = {doi.org/10.48550/arXiv.2412.00213},
year = {2024},
date = {2024-11-29},
urldate = {2024-11-29},
abstract = {Non-projective measurements are resourceful in several information-processing protocols. In this work, we propose an operational task involving space-like separated parties to detect measurements that are neither projective nor a classical post-processing of data obtained from a projective measurement. In the case of qubits, we consider a bipartite scenario and different sets of target correlations. While some correlations in each of these sets can be obtained by performing non-projective measurements on some shared two-qubit state it is impossible to simulate correlation in any of them using projective simulable measurements on bipartite qubit states or equivalently one bit of shared randomness. While considering certain sets of target correlations we show that the detection of qubit non-projective measurement is robust under arbitrary depolarising noise (except in the limiting case). For qutrits, while considering a similar task we show that some correlations obtained from local non-projective measurements are impossible to be obtained while performing the same qutrit projective simulable measurements by both parties. We provide numerical evidence of its robustness under arbitrary depolarising noise. For a more generic consideration (bipartite and tripartite scenario), we provide numerical evidence for a projective-simulable bound on the reward function for our task. We also show a violation of this bound by using qutrit POVMs. From a foundational perspective, we extend the notion of non-projective measurements to general probabilistic theories (GPTs) and use a randomness-free test to demonstrate that a class of GPTs, called square-bits or box-world are unphysical.},
keywords = {UAB},
pubstate = {published},
tppubtype = {workingpaper}
}
Non-projective measurements are resourceful in several information-processing protocols. In this work, we propose an operational task involving space-like separated parties to detect measurements that are neither projective nor a classical post-processing of data obtained from a projective measurement. In the case of qubits, we consider a bipartite scenario and different sets of target correlations. While some correlations in each of these sets can be obtained by performing non-projective measurements on some shared two-qubit state it is impossible to simulate correlation in any of them using projective simulable measurements on bipartite qubit states or equivalently one bit of shared randomness. While considering certain sets of target correlations we show that the detection of qubit non-projective measurement is robust under arbitrary depolarising noise (except in the limiting case). For qutrits, while considering a similar task we show that some correlations obtained from local non-projective measurements are impossible to be obtained while performing the same qutrit projective simulable measurements by both parties. We provide numerical evidence of its robustness under arbitrary depolarising noise. For a more generic consideration (bipartite and tripartite scenario), we provide numerical evidence for a projective-simulable bound on the reward function for our task. We also show a violation of this bound by using qutrit POVMs. From a foundational perspective, we extend the notion of non-projective measurements to general probabilistic theories (GPTs) and use a randomness-free test to demonstrate that a class of GPTs, called square-bits or box-world are unphysical.
Rout, S.; N. Bhattacharya Sakharwade, S. S.; Ramanathan, R.; Horodecki, P.
Unbounded Quantum Advantage in Communication with Minimal Input Scaling Working paper
Preprint, 2024.
Resumen | Enlaces | BibTeX | Etiquetas: UAB
@workingpaper{nokey,
title = {Unbounded Quantum Advantage in Communication with Minimal Input Scaling},
author = {Rout,S. and Sakharwade, N. Bhattacharya, S.S. and Ramanathan, R. and Horodecki, P.},
url = {https://arxiv.org/pdf/2305.10372},
doi = {doi.org/10.48550/arXiv.2305.10372},
year = {2024},
date = {2024-11-29},
urldate = {2024-11-29},
abstract = {In communication complexity-like problems, previous studies have shown either an exponential quantum advantage or an unbounded quantum advantage with an exponentially large input set Θ(2n) bits with respect to classical communication Θ(n) bits. In the former, the quantum and classical separation grows exponentially in input while the latter's quantum communication resource is a constant. Remarkably, it was still open whether an unbounded quantum advantage exists while the inputs do not scale exponentially. Here we answer this question affirmatively using an input size of optimal order. Considering two variants as tasks: 1) distributed computation of relation and 2) {it relation reconstruction}, we study the one-way zero-error communication complexity of a relation induced by a distributed clique labelling problem for orthogonality graphs. While we prove no quantum advantage in the first task, we show an {it unbounded quantum advantage} in relation reconstruction without public coins. Specifically, for a class of graphs with order m, the quantum complexity is Θ(1) while the classical complexity is Θ(logm). Remarkably, the input size is Θ(logm) bits and the order of its scaling with respect to classical communication is {it minimal}. This is exponentially better compared to previous works. Additionally, we prove a lower bound (linear in the number of maximum cliques) on the amount of classical public coin necessary to overcome the separation in the scenario of restricted communication and connect this to the existence of Orthogonal Arrays. Finally, we highlight some applications of this task to semi-device-independent dimension witnessing as well as to the detection of Mutually Unbiased Bases.},
howpublished = {Preprint},
keywords = {UAB},
pubstate = {published},
tppubtype = {workingpaper}
}
In communication complexity-like problems, previous studies have shown either an exponential quantum advantage or an unbounded quantum advantage with an exponentially large input set Θ(2n) bits with respect to classical communication Θ(n) bits. In the former, the quantum and classical separation grows exponentially in input while the latter's quantum communication resource is a constant. Remarkably, it was still open whether an unbounded quantum advantage exists while the inputs do not scale exponentially. Here we answer this question affirmatively using an input size of optimal order. Considering two variants as tasks: 1) distributed computation of relation and 2) {it relation reconstruction}, we study the one-way zero-error communication complexity of a relation induced by a distributed clique labelling problem for orthogonality graphs. While we prove no quantum advantage in the first task, we show an {it unbounded quantum advantage} in relation reconstruction without public coins. Specifically, for a class of graphs with order m, the quantum complexity is Θ(1) while the classical complexity is Θ(logm). Remarkably, the input size is Θ(logm) bits and the order of its scaling with respect to classical communication is {it minimal}. This is exponentially better compared to previous works. Additionally, we prove a lower bound (linear in the number of maximum cliques) on the amount of classical public coin necessary to overcome the separation in the scenario of restricted communication and connect this to the existence of Orthogonal Arrays. Finally, we highlight some applications of this task to semi-device-independent dimension witnessing as well as to the detection of Mutually Unbiased Bases.
Mariella, N.; Murphy, T.; Di Marcantonio, F.; Najafi, K.; Vallecorsa, S.; Zhuk, S.; Rico, E.
Order Parameter Discovery for Quantum Many-Body Systems Working paper
Preprint, 2024.
Resumen | Enlaces | BibTeX | Etiquetas: UPV/EHU
@workingpaper{nokey,
title = {Order Parameter Discovery for Quantum Many-Body Systems},
author = {Mariella, N. and Murphy, T. and Di Marcantonio, F. and Najafi, K. and Vallecorsa, S. and Zhuk, S. and Rico, E.},
url = {https://arxiv.org/abs/2408.01400},
doi = {doi.org/10.48550/arXiv.2408.01400},
year = {2024},
date = {2024-11-18},
urldate = {2024-11-18},
abstract = {Quantum phase transitions reveal deep insights into the behavior of many-body quantum systems, but identifying these transitions without well-defined order parameters remains a significant challenge. In this work, we introduce a novel approach to constructing phase diagrams using the vector field of the reduced fidelity susceptibility (RFS). This method maps quantum phases and formulates an optimization problem to discover observables corresponding to order parameters. We demonstrate the effectiveness of our approach by applying it to well-established models, including the Axial Next Nearest Neighbour Interaction (ANNNI) model, a cluster state model, and a chain of Rydberg atoms. By analyzing observable decompositions into eigen-projectors and finite-size scaling, our method successfully identifies order parameters and characterizes quantum phase transitions with high precision. Our results provide a powerful tool for exploring quantum phases in systems where conventional order parameters are not readily available.},
howpublished = {Preprint},
keywords = {UPV/EHU},
pubstate = {published},
tppubtype = {workingpaper}
}
Quantum phase transitions reveal deep insights into the behavior of many-body quantum systems, but identifying these transitions without well-defined order parameters remains a significant challenge. In this work, we introduce a novel approach to constructing phase diagrams using the vector field of the reduced fidelity susceptibility (RFS). This method maps quantum phases and formulates an optimization problem to discover observables corresponding to order parameters. We demonstrate the effectiveness of our approach by applying it to well-established models, including the Axial Next Nearest Neighbour Interaction (ANNNI) model, a cluster state model, and a chain of Rydberg atoms. By analyzing observable decompositions into eigen-projectors and finite-size scaling, our method successfully identifies order parameters and characterizes quantum phase transitions with high precision. Our results provide a powerful tool for exploring quantum phases in systems where conventional order parameters are not readily available.
Palacios, A.; Martínez-Pena, R.; Soriano, M. C.; Giorgi, G. L.; Zambrini, R.
Role of coherence in many-body Quantum Reservoir Computing Artículo de revista
En: Communications Physics, vol. 7, no 369, 2024.
Resumen | Enlaces | BibTeX | Etiquetas: UIB
@article{nokey,
title = {Role of coherence in many-body Quantum Reservoir Computing},
author = {Palacios, A. and Martínez-Pena, R. and Soriano, M.C. and Giorgi, G.L. and Zambrini, R. },
url = {https://www.nature.com/articles/s42005-024-01859-4},
doi = {doi.org/10.1038/s42005-024-01859-4},
year = {2024},
date = {2024-11-14},
urldate = {2024-11-14},
journal = {Communications Physics},
volume = {7},
number = {369},
abstract = {Quantum Reservoir Computing (QRC) offers potential advantages over classical reservoir computing, including inherent processing of quantum inputs and a vast Hilbert space for state exploration. Yet, the relation between the performance of reservoirs based on complex and many-body quantum systems and non-classical state features is not established. Through an extensive analysis of QRC based on a transverse-field Ising model we show how different quantum effects, such as quantum
coherence and correlations, contribute to improving the performance in temporal tasks, as measured by the Information Processing Capacity. Additionally, we critically assess the impact of finite measurement resources and noise on the reservoir’s dynamics in different regimes, quantifying the limited ability to exploit quantum effects for increasing damping and noise strengths. Our results reveal a monotonic relationship between reservoir performance and coherence, along with the importance of quantum effects in the ergodic regime.},
keywords = {UIB},
pubstate = {published},
tppubtype = {article}
}
Quantum Reservoir Computing (QRC) offers potential advantages over classical reservoir computing, including inherent processing of quantum inputs and a vast Hilbert space for state exploration. Yet, the relation between the performance of reservoirs based on complex and many-body quantum systems and non-classical state features is not established. Through an extensive analysis of QRC based on a transverse-field Ising model we show how different quantum effects, such as quantum
coherence and correlations, contribute to improving the performance in temporal tasks, as measured by the Information Processing Capacity. Additionally, we critically assess the impact of finite measurement resources and noise on the reservoir’s dynamics in different regimes, quantifying the limited ability to exploit quantum effects for increasing damping and noise strengths. Our results reveal a monotonic relationship between reservoir performance and coherence, along with the importance of quantum effects in the ergodic regime.
coherence and correlations, contribute to improving the performance in temporal tasks, as measured by the Information Processing Capacity. Additionally, we critically assess the impact of finite measurement resources and noise on the reservoir’s dynamics in different regimes, quantifying the limited ability to exploit quantum effects for increasing damping and noise strengths. Our results reveal a monotonic relationship between reservoir performance and coherence, along with the importance of quantum effects in the ergodic regime.
Tang, J.; Xu, R.; Ding, Y.; Xu, X.; Ban, Y.; Yung, M. H.; Pérez-Obiol, A.; G. Chen Platero, Xi.
Exploring ground states of Fermi-Hubbard model on honeycomb lattices with counterdiabaticity Artículo de revista
En: Quantum Materials , vol. 9, no 87, 2024.
Resumen | Enlaces | BibTeX | Etiquetas: UPV/EHU
@article{nokey,
title = {Exploring ground states of Fermi-Hubbard model on honeycomb lattices with counterdiabaticity},
author = {Tang, J. and Xu, R. and Ding, Y. and Xu, X. and Ban, Y. and Yung, M.H. and Pérez-Obiol, A. and Platero, G. Chen, Xi.},
url = {https://www.nature.com/articles/s41535-024-00697-5},
doi = {doi.org/10.1038/s41535-024-00697-5},
year = {2024},
date = {2024-11-07},
journal = {Quantum Materials },
volume = {9},
number = {87},
abstract = {Exploring the ground state properties of many-body quantum systems conventionally involves adiabatic processes, alongside exact diagonalization, in the context of quantum annealing or adiabatic quantum computation. Shortcuts to adiabaticity by counter-diabatic driving serve to accelerate these processes by suppressing energy excitations. Motivated by this, we develop variational quantum algorithms incorporating the auxiliary counter-diabatic interactions, comparing them with digitized adiabatic algorithms. These algorithms are then implemented on gate-based quantum circuits to explore the ground states of the Fermi-Hubbard model on honeycomb lattices, utilizing systems with up to 26 qubits. The comparison reveals that the counter-diabatic inspired ansatz is superior to traditional Hamiltonian variational ansatz. Furthermore, the number and duration of Trotter steps are analyzed to understand and mitigate errors. Given the model’s relevance to materials in condensed matter, our study paves the way for using variational quantum algorithms with counterdiabaticity to explore quantum materials in the noisy intermediate-scale quantum era.},
keywords = {UPV/EHU},
pubstate = {published},
tppubtype = {article}
}
Exploring the ground state properties of many-body quantum systems conventionally involves adiabatic processes, alongside exact diagonalization, in the context of quantum annealing or adiabatic quantum computation. Shortcuts to adiabaticity by counter-diabatic driving serve to accelerate these processes by suppressing energy excitations. Motivated by this, we develop variational quantum algorithms incorporating the auxiliary counter-diabatic interactions, comparing them with digitized adiabatic algorithms. These algorithms are then implemented on gate-based quantum circuits to explore the ground states of the Fermi-Hubbard model on honeycomb lattices, utilizing systems with up to 26 qubits. The comparison reveals that the counter-diabatic inspired ansatz is superior to traditional Hamiltonian variational ansatz. Furthermore, the number and duration of Trotter steps are analyzed to understand and mitigate errors. Given the model’s relevance to materials in condensed matter, our study paves the way for using variational quantum algorithms with counterdiabaticity to explore quantum materials in the noisy intermediate-scale quantum era.
Abellanet-Vidal, J.; Müller-Rigat, G.; Rajchel-Mieldzioć, G.; Sanpera, A.
Improving absolute separability bounds for arbitrary dimensions Working paper
2024.
Resumen | Enlaces | BibTeX | Etiquetas: UAB
@workingpaper{nokey,
title = {Improving absolute separability bounds for arbitrary dimensions},
author = {Abellanet-Vidal, J. and Müller-Rigat, G. and Rajchel-Mieldzioć, G. and Sanpera, A.},
url = {https://arxiv.org/abs/2410.22415},
doi = {doi.org/10.48550/arXiv.2410.22415},
year = {2024},
date = {2024-10-29},
urldate = {2024-10-29},
abstract = {Sufficient analytical conditions for separability in composite quantum systems are very scarce and only known for low-dimensional cases. Here, we use linear maps and their inverses to derive powerful analytical conditions, providing tight bounds and extremal points of the set of absolutely separable states, i.e., states that remain separable under any global unitary transformation. Our analytical results apply to generic quantum states in arbitrary dimensions, and depend only on a single or very few eigenvalues of the considered state. Furthermore, we use convex geometry tools to improve the general characterization of the AS set given several non-comparable criteria. Finally, we present various conditions related to the twin problem of characterizing absolute PPT, that is, the set of quantum states that are positive under partial transposition and remain so under all unitary transformations.},
keywords = {UAB},
pubstate = {published},
tppubtype = {workingpaper}
}
Sufficient analytical conditions for separability in composite quantum systems are very scarce and only known for low-dimensional cases. Here, we use linear maps and their inverses to derive powerful analytical conditions, providing tight bounds and extremal points of the set of absolutely separable states, i.e., states that remain separable under any global unitary transformation. Our analytical results apply to generic quantum states in arbitrary dimensions, and depend only on a single or very few eigenvalues of the considered state. Furthermore, we use convex geometry tools to improve the general characterization of the AS set given several non-comparable criteria. Finally, we present various conditions related to the twin problem of characterizing absolute PPT, that is, the set of quantum states that are positive under partial transposition and remain so under all unitary transformations.
Farreras, M.; Cervera-Lierta, A.
Simulation of the 1d XY model on a quantum computer Working paper
Preprint, 2024.
Enlaces | BibTeX | Etiquetas: BSC
@workingpaper{nokey,
title = {Simulation of the 1d XY model on a quantum computer},
author = {Farreras, M. and Cervera-Lierta, A.},
url = {https://doi.org/10.48550/arXiv.2410.21143
},
doi = {doi.org/10.48550/arXiv.2410.21143},
year = {2024},
date = {2024-10-28},
urldate = {2024-10-28},
howpublished = {Preprint},
keywords = {BSC},
pubstate = {published},
tppubtype = {workingpaper}
}
Florido-Llinàs, M.; Alhambra, A. M.; Trivedi, R.; N. Pérez-García Schuch, D.; Cirac, J. I.
The product structure of MPS-under-permutations Working paper
2024.
Resumen | Enlaces | BibTeX | Etiquetas: UCM-4.2
@workingpaper{nokey,
title = {The product structure of MPS-under-permutations},
author = {Florido-Llinàs, M. and Alhambra, A.M. and Trivedi, R. and Schuch, N. Pérez-García, D. and Cirac, J.I. },
url = {https://arxiv.org/abs/2410.19541},
doi = {doi.org/10.48550/arXiv.2410.19541},
year = {2024},
date = {2024-10-25},
abstract = {Tensor network methods have proved to be highly effective in addressing a wide variety of physical scenarios, including those lacking an intrinsic one-dimensional geometry. In such contexts, it is possible for the problem to exhibit a weak form of permutational symmetry, in the sense that entanglement behaves similarly across any arbitrary bipartition. In this paper, we show that translationally-invariant (TI) matrix product states (MPS) with this property are trivial, meaning that they are either product states or superpositions of a few of them. The results also apply to non-TI generic MPS, as well as further relevant examples of MPS including the W state and the Dicke states in an approximate sense. Our findings motivate the usage of ansätze simpler than tensor networks in systems whose structure is invariant under permutations.},
keywords = {UCM-4.2},
pubstate = {published},
tppubtype = {workingpaper}
}
Tensor network methods have proved to be highly effective in addressing a wide variety of physical scenarios, including those lacking an intrinsic one-dimensional geometry. In such contexts, it is possible for the problem to exhibit a weak form of permutational symmetry, in the sense that entanglement behaves similarly across any arbitrary bipartition. In this paper, we show that translationally-invariant (TI) matrix product states (MPS) with this property are trivial, meaning that they are either product states or superpositions of a few of them. The results also apply to non-TI generic MPS, as well as further relevant examples of MPS including the W state and the Dicke states in an approximate sense. Our findings motivate the usage of ansätze simpler than tensor networks in systems whose structure is invariant under permutations.
Fanchiotti, H.; García-Canal, C. A.; Mayosky, M.; Pérez, A.; Veiga, A.
Quantum and classical dynamics correspondence and the brachistochrone problem Artículo de revista
En: Physical Review A, vol. 110, iss. 4, 2024, ISSN: 2469-9926 .
Resumen | Enlaces | BibTeX | Etiquetas: UV
@article{nokey,
title = {Quantum and classical dynamics correspondence and the brachistochrone problem},
author = {Fanchiotti, H. and García-Canal, C.A. and Mayosky, M. and Pérez, A. and Veiga, A. },
url = {https://journals.aps.org/pra/abstract/10.1103/PhysRevA.110.042219},
doi = {doi.org/10.1103/PhysRevA.110.042219},
issn = {2469-9926 },
year = {2024},
date = {2024-10-22},
journal = {Physical Review A},
volume = {110},
issue = {4},
abstract = {The decomplexification procedure, which allows showing mathematically the isomorphism between classical and quantum dynamics of systems with a finite number of basis states, is exploited to propose resonant electric circuits with gyrator-based couplings and to experimentally study the quantum brachistochrone problem, particularly the passage time in Hermitian and parity-time-symmetric cases.},
keywords = {UV},
pubstate = {published},
tppubtype = {article}
}
The decomplexification procedure, which allows showing mathematically the isomorphism between classical and quantum dynamics of systems with a finite number of basis states, is exploited to propose resonant electric circuits with gyrator-based couplings and to experimentally study the quantum brachistochrone problem, particularly the passage time in Hermitian and parity-time-symmetric cases.
Bottarelli, A.; Garcia de Andoin, M.; Chandarana, P.; Paul, K.; Chen, X.; Sanz, M.; Hauke, P.
Symmetry-enhanced Counterdiabatic Quantum Algorithm for Qudits Working paper
2024.
Resumen | Enlaces | BibTeX | Etiquetas: UPV/EHU
@workingpaper{nokey,
title = {Symmetry-enhanced Counterdiabatic Quantum Algorithm for Qudits},
author = {Bottarelli, A. and Garcia de Andoin, M. and Chandarana, P. and Paul, K. and Chen, X. and Sanz, M. and Hauke, P.},
url = {https://arxiv.org/abs/2410.06710},
doi = {doi.org/10.48550/arXiv.2410.06710},
year = {2024},
date = {2024-10-18},
abstract = {Qubit-based variational quantum algorithms have undergone rapid development in recent years but still face several challenges. In this context, we propose a symmetry-enhanced digitized counterdiabatic quantum algorithm utilizing qudits instead of qubits. This approach offers three types of compression as compared to with respect to conventional variational circuits. First, compression in the circuit depth is achieved by counterdiabatic protocols. Second, information about the problem is compressed by replacing qubits with qudits, allowing for a more efficient representation of the problem. Lastly, the number of parameters is reduced by employing the symmetries of the system. We illustrate this approach by tackling a graph-based optimization problem Max-3-Cut and a highly-entangled state preparation, the qutrit W state. As our numerical results show, we achieve a better convergence with a lower circuit depth and less measurement overhead in all the cases considered. This work leads to a better design of shallow variational quantum circuits, improving the feasibility of their implementation on near-term qudit devices},
keywords = {UPV/EHU},
pubstate = {published},
tppubtype = {workingpaper}
}
Qubit-based variational quantum algorithms have undergone rapid development in recent years but still face several challenges. In this context, we propose a symmetry-enhanced digitized counterdiabatic quantum algorithm utilizing qudits instead of qubits. This approach offers three types of compression as compared to with respect to conventional variational circuits. First, compression in the circuit depth is achieved by counterdiabatic protocols. Second, information about the problem is compressed by replacing qubits with qudits, allowing for a more efficient representation of the problem. Lastly, the number of parameters is reduced by employing the symmetries of the system. We illustrate this approach by tackling a graph-based optimization problem Max-3-Cut and a highly-entangled state preparation, the qutrit W state. As our numerical results show, we achieve a better convergence with a lower circuit depth and less measurement overhead in all the cases considered. This work leads to a better design of shallow variational quantum circuits, improving the feasibility of their implementation on near-term qudit devices
Ugo Nzongani, U.; Eon, N.; Márquez-Martín, I.; Pérez, A.; Di Molfetta, G.; Arrighi, P.
Dirac quantum walk on tetrahedra Artículo de revista
En: Physical Review A, vol. 110, iss. 4, 2024, ISSN: 2469-9926 .
Resumen | Enlaces | BibTeX | Etiquetas: UV
@article{nokey,
title = {Dirac quantum walk on tetrahedra},
author = {Ugo Nzongani, U. and Eon, N. and Márquez-Martín, I. and Pérez, A. and Di Molfetta, G. and Arrighi, P.},
url = {https://journals.aps.org/pra/abstract/10.1103/PhysRevA.110.042418},
doi = {doi.org/10.1103/PhysRevA.110.042418},
issn = {2469-9926 },
year = {2024},
date = {2024-10-16},
journal = {Physical Review A},
volume = {110},
issue = {4},
abstract = {Discrete-time quantum walks (QWs) are transportation models of single quantum particles over a lattice. Their evolution is driven through causal and local unitary operators. QWs are a powerful tool for quantum simulation of fundamental physics, as some of them have a continuum limit converging to well-known physics partial differential equations, such as the Dirac or the Schrödinger equation. In this paper, we show how to recover the Dirac equation in (3+1) dimensions with a QW evolving in a tetrahedral space. This paves the way to simulate the Dirac equation on a curved space-time. This also suggests an ordered scheme for propagating matter over a spin network, of interest in loop quantum gravity, where matter propagation has remained an open problem.},
keywords = {UV},
pubstate = {published},
tppubtype = {article}
}
Discrete-time quantum walks (QWs) are transportation models of single quantum particles over a lattice. Their evolution is driven through causal and local unitary operators. QWs are a powerful tool for quantum simulation of fundamental physics, as some of them have a continuum limit converging to well-known physics partial differential equations, such as the Dirac or the Schrödinger equation. In this paper, we show how to recover the Dirac equation in (3+1) dimensions with a QW evolving in a tetrahedral space. This paves the way to simulate the Dirac equation on a curved space-time. This also suggests an ordered scheme for propagating matter over a spin network, of interest in loop quantum gravity, where matter propagation has remained an open problem.
Piccolini, M.; Karczewski, M.; Winter, A.; Lo Franco, R.
Robust generation of N-partite N-level singlet states by identical particle interferometry Artículo de revista
En: Quantum Science and Technology, vol. 10, iss. 1, no 15013 , 2024.
Resumen | Enlaces | BibTeX | Etiquetas: UAB
@article{nokey,
title = {Robust generation of N-partite N-level singlet states by identical particle interferometry},
author = {Piccolini, M. and Karczewski, M. and Winter, A. and Lo Franco, R. },
url = {https://iopscience.iop.org/article/10.1088/2058-9565/ad8214},
doi = {10.1088/2058-9565/ad8214},
year = {2024},
date = {2024-10-15},
journal = {Quantum Science and Technology},
volume = {10},
number = {15013 },
issue = {1},
abstract = {We propose an interferometric scheme for generating the totally antisymmetric state of N identical bosons with N internal levels (generalized singlet). This state is a resource for various problems with dramatic quantum advantage. The procedure uses a sequence of Fourier multi-ports, combined with coincidence measurements filtering the results. Successful preparation of the generalized singlet is confirmed when the N particles of the input state stay separate (anti-bunch) on each multiport. The scheme is robust to local lossless noise and works even with a totally mixed input state.},
keywords = {UAB},
pubstate = {published},
tppubtype = {article}
}
We propose an interferometric scheme for generating the totally antisymmetric state of N identical bosons with N internal levels (generalized singlet). This state is a resource for various problems with dramatic quantum advantage. The procedure uses a sequence of Fourier multi-ports, combined with coincidence measurements filtering the results. Successful preparation of the generalized singlet is confirmed when the N particles of the input state stay separate (anti-bunch) on each multiport. The scheme is robust to local lossless noise and works even with a totally mixed input state.
deMarti iOlius, A.; Fuentes, P.; Orús, R.; Crespo, P.; Etxezarreta Martinez, J.
Decoding algorithms for surface codes Artículo de revista
En: Quantum, vol. 8, pp. 1498, 2024, ISBN: 2521-327X.
Resumen | Enlaces | BibTeX | Etiquetas: TECNUN
@article{nokey,
title = {Decoding algorithms for surface codes},
author = {deMarti iOlius, A. and Fuentes, P. and Orús, R. and Crespo, P. and Etxezarreta Martinez, J. },
url = {https://quantum-journal.org/papers/q-2024-10-10-1498/pdf/},
doi = {doi.org/10.22331/q-2024-10-10-1498},
isbn = {2521-327X},
year = {2024},
date = {2024-10-10},
journal = {Quantum},
volume = {8},
pages = {1498},
abstract = {Quantum technologies have the potential to solve certain computationally hard problems with polynomial or super-polynomial speedups when compared to classical methods. Unfortunately, the unstable nature of quantum information makes it prone to errors. For this reason, quantum error correction is an invaluable tool to make quantum information reliable and enable the ultimate goal of fault-tolerant quantum computing. Surface codes currently stand as the most promising candidates to build near term error corrected qubits given their two-dimensional architecture, the requirement of only local operations, and high tolerance to quantum noise. Decoding algorithms are an integral component of any error correction scheme, as they are tasked with producing accurate estimates of the errors that affect quantum information, so that they can subsequently be corrected. A critical aspect of decoding algorithms is their speed, since the quantum state will suffer additional errors with the passage of time. This poses a connundrum, where decoding performance is improved at the expense of complexity and viceversa. In this review, a thorough discussion of state-of-the-art decoding algorithms for surface codes is provided. The target audience of this work are both readers with an introductory understanding of the field as well as those seeking to further their knowledge of the decoding paradigm of surface codes. We describe the core principles of these decoding methods as well as existing variants that show promise for improved results. In addition, both the decoding performance, in terms of error correction capability, and decoding complexity, are compared. A review of the existing software tools regarding surface codes decoding is also provided.},
keywords = {TECNUN},
pubstate = {published},
tppubtype = {article}
}
Quantum technologies have the potential to solve certain computationally hard problems with polynomial or super-polynomial speedups when compared to classical methods. Unfortunately, the unstable nature of quantum information makes it prone to errors. For this reason, quantum error correction is an invaluable tool to make quantum information reliable and enable the ultimate goal of fault-tolerant quantum computing. Surface codes currently stand as the most promising candidates to build near term error corrected qubits given their two-dimensional architecture, the requirement of only local operations, and high tolerance to quantum noise. Decoding algorithms are an integral component of any error correction scheme, as they are tasked with producing accurate estimates of the errors that affect quantum information, so that they can subsequently be corrected. A critical aspect of decoding algorithms is their speed, since the quantum state will suffer additional errors with the passage of time. This poses a connundrum, where decoding performance is improved at the expense of complexity and viceversa. In this review, a thorough discussion of state-of-the-art decoding algorithms for surface codes is provided. The target audience of this work are both readers with an introductory understanding of the field as well as those seeking to further their knowledge of the decoding paradigm of surface codes. We describe the core principles of these decoding methods as well as existing variants that show promise for improved results. In addition, both the decoding performance, in terms of error correction capability, and decoding complexity, are compared. A review of the existing software tools regarding surface codes decoding is also provided.
Lamata, L.; Llenas, A.
Digital-analog quantum genetic algorithm using Rydberg-atom arrays Artículo de revista
En: Physical Review A, vol. 110, iss. 4, 2024.
Resumen | Enlaces | BibTeX | Etiquetas: US
@article{nokey,
title = {Digital-analog quantum genetic algorithm using Rydberg-atom arrays},
author = {Lamata, L. and Llenas, A. },
url = {https://arxiv.org/pdf/2407.09308},
doi = {doi.org/10.1103/PhysRevA.110.042603},
year = {2024},
date = {2024-10-03},
urldate = {2024-10-03},
journal = {Physical Review A},
volume = {110},
issue = {4},
abstract = {Digital-analog quantum computing (DAQC) combines digital gates with analog operations, offering an alternative paradigm for universal quantum computation. This approach leverages the higher fidelities of analog operations and the flexibility of local single-qubit gates. In this paper, we propose a quantum genetic algorithm within the DAQC framework using a Rydberg-atom emulator. The algorithm employs single-qubit operations in the digital domain and a global driving interaction based on the Rydberg Hamiltonian in the analog domain. We evaluate the algorithm performance by estimating the ground-state energy of Hamiltonians, with a focus on molecules such as H2, LiH, and BeH2. Our results show energy estimations with less than 1% error and state overlaps nearing 1, with computation times ranging from a few minutes for H2 (2-qubit circuits) to one to two days for LiH and BeH2 (6-qubit circuits). The gate fidelities of global analog operations further underscore DAQC as a promising quantum computing strategy in the noisy intermediate-scale quantum era.},
keywords = {US},
pubstate = {published},
tppubtype = {article}
}
Digital-analog quantum computing (DAQC) combines digital gates with analog operations, offering an alternative paradigm for universal quantum computation. This approach leverages the higher fidelities of analog operations and the flexibility of local single-qubit gates. In this paper, we propose a quantum genetic algorithm within the DAQC framework using a Rydberg-atom emulator. The algorithm employs single-qubit operations in the digital domain and a global driving interaction based on the Rydberg Hamiltonian in the analog domain. We evaluate the algorithm performance by estimating the ground-state energy of Hamiltonians, with a focus on molecules such as H2, LiH, and BeH2. Our results show energy estimations with less than 1% error and state overlaps nearing 1, with computation times ranging from a few minutes for H2 (2-qubit circuits) to one to two days for LiH and BeH2 (6-qubit circuits). The gate fidelities of global analog operations further underscore DAQC as a promising quantum computing strategy in the noisy intermediate-scale quantum era.
Pranav, C.; Koushik, P.; Garcia-de-Andoin, M.; Ban, Y.; Sanz, M.; Chen, X.
Photonic counterdiabatic quantum optimization algorithm Artículo de revista
En: Communications Physics, no 315, 2024, ISBN: 2399-3650.
Resumen | Enlaces | BibTeX | Etiquetas: UPV/EHU
@article{nokey,
title = {Photonic counterdiabatic quantum optimization algorithm},
author = {Pranav, C. and Koushik, P. and Garcia-de-Andoin, M. and Ban, Y. and Sanz, M. and Chen, X.},
url = {https://www.nature.com/articles/s42005-024-01807-2.pdf},
doi = {doi.org/10.1038/s42005-024-01807-2},
isbn = {2399-3650},
year = {2024},
date = {2024-09-30},
journal = {Communications Physics},
number = {315},
abstract = {One of the key applications of near-term quantum computers has been the development of quantum optimization algorithms. However, these algorithms have largely been focused on qubit-based technologies. Here, we propose a hybrid quantum-classical approximate optimization algorithm for photonic quantum computing, specifically tailored for addressing continuous-variable optimization problems. Inspired by counterdiabatic protocols, our algorithm reduces the required quantum operations for optimization compared to adiabatic protocols. This reduction enables us to tackle non-convex continuous optimization within the near-term era of quantum computing. Through illustrative benchmarking, we show that our approach can outperform existing state-of-the-art hybrid adiabatic quantum algorithms in terms of convergence and implementability. Our algorithm offers a practical and accessible experimental realization, bypassing the need for high-order operations and overcoming experimental constraints. We conduct a proof-of-principle demonstration on Xanadu’s eight-mode nanophotonic quantum chip, successfully showcasing the feasibility and potential impact of the algorithm.},
keywords = {UPV/EHU},
pubstate = {published},
tppubtype = {article}
}
One of the key applications of near-term quantum computers has been the development of quantum optimization algorithms. However, these algorithms have largely been focused on qubit-based technologies. Here, we propose a hybrid quantum-classical approximate optimization algorithm for photonic quantum computing, specifically tailored for addressing continuous-variable optimization problems. Inspired by counterdiabatic protocols, our algorithm reduces the required quantum operations for optimization compared to adiabatic protocols. This reduction enables us to tackle non-convex continuous optimization within the near-term era of quantum computing. Through illustrative benchmarking, we show that our approach can outperform existing state-of-the-art hybrid adiabatic quantum algorithms in terms of convergence and implementability. Our algorithm offers a practical and accessible experimental realization, bypassing the need for high-order operations and overcoming experimental constraints. We conduct a proof-of-principle demonstration on Xanadu’s eight-mode nanophotonic quantum chip, successfully showcasing the feasibility and potential impact of the algorithm.
P. Koushik Chandarana, P.; Kasturi Ranjan, S.; Chen, X.; Del Campo, A.
Lyapunov Controlled Counterdiabatic Quantum Optimization Working paper
Preprint, 2024.
Resumen | Enlaces | BibTeX | Etiquetas: UPV/EHU
@workingpaper{nokey,
title = {Lyapunov Controlled Counterdiabatic Quantum Optimization},
author = {Chandarana, P. Koushik, P. and Kasturi Ranjan, S. and Chen, X. and Del Campo, A. },
url = {https://arxiv.org/pdf/2409.12525},
doi = {doi.org/10.48550/arXiv.2409.12525},
year = {2024},
date = {2024-09-19},
urldate = {2024-09-19},
abstract = {We introduce a quantum algorithm integrating counterdiabatic (CD) protocols with quantum Lyapunov control (QLC) to tackle combinatorial optimization problems. This approach offers versatility, allowing implementation as either a digital-analog or purely digital algorithm based on selected control strategies. By examining spin-glass Hamiltonians, we illustrate how the algorithm can explore alternative paths to enhance solution outcomes compared to conventional CD techniques. This method reduces the dependence on extensive higher-order CD terms and classical optimization techniques, rendering it more suitable for existing quantum computing platforms. The combination of digital compression via CD protocols and the adaptable nature of QLC methods positions this approach as a promising candidate for near-term quantum computing.},
howpublished = {Preprint},
keywords = {UPV/EHU},
pubstate = {published},
tppubtype = {workingpaper}
}
We introduce a quantum algorithm integrating counterdiabatic (CD) protocols with quantum Lyapunov control (QLC) to tackle combinatorial optimization problems. This approach offers versatility, allowing implementation as either a digital-analog or purely digital algorithm based on selected control strategies. By examining spin-glass Hamiltonians, we illustrate how the algorithm can explore alternative paths to enhance solution outcomes compared to conventional CD techniques. This method reduces the dependence on extensive higher-order CD terms and classical optimization techniques, rendering it more suitable for existing quantum computing platforms. The combination of digital compression via CD protocols and the adaptable nature of QLC methods positions this approach as a promising candidate for near-term quantum computing.
Fontana, P.; Miranda Riaza, M.; Celi, A.
An efficient finite-resource formulation of non-Abelian lattice gauge theories beyond one dimension Working paper
2024.
Resumen | Enlaces | BibTeX | Etiquetas: UAB
@workingpaper{nokey,
title = {An efficient finite-resource formulation of non-Abelian lattice gauge theories beyond one dimension},
author = {Fontana, P. and Miranda Riaza, M. and Celi, A.},
url = {https://arxiv.org/abs/2409.04441},
doi = {doi.org/10.48550/arXiv.2409.04441},
year = {2024},
date = {2024-09-06},
abstract = {Non-Abelian gauge theories provide an accurate description of fundamental interactions, as both perturbation theory and quantum Monte Carlo computations in lattice gauge theory, it when applicable, show remarkable agreement with experimental data from particle colliders and cosmological observations. Complementing these computations, or combining them with quantum-inspired Hamiltonian lattice computations on quantum machines to improve continuum limit predictions with current quantum resources, is a formidable open challenge. Here, we propose a resource-efficient method to compute the running of the coupling in non-Abelian gauge theories beyond one spatial dimension. We first represent the Hamiltonian on periodic lattices in terms of loop variables and conjugate loop electric fields, exploiting the Gauss law to retain the gauge-independent ones. Then, we identify a local basis for small and large loops variationally to minimize the truncation error while computing the running of the coupling on small tori. Our method enables computations at arbitrary values of the bare coupling and lattice spacing with current quantum computers, simulators and tensor-network calculations, in regimes otherwise inaccessible.},
keywords = {UAB},
pubstate = {published},
tppubtype = {workingpaper}
}
Non-Abelian gauge theories provide an accurate description of fundamental interactions, as both perturbation theory and quantum Monte Carlo computations in lattice gauge theory, it when applicable, show remarkable agreement with experimental data from particle colliders and cosmological observations. Complementing these computations, or combining them with quantum-inspired Hamiltonian lattice computations on quantum machines to improve continuum limit predictions with current quantum resources, is a formidable open challenge. Here, we propose a resource-efficient method to compute the running of the coupling in non-Abelian gauge theories beyond one spatial dimension. We first represent the Hamiltonian on periodic lattices in terms of loop variables and conjugate loop electric fields, exploiting the Gauss law to retain the gauge-independent ones. Then, we identify a local basis for small and large loops variationally to minimize the truncation error while computing the running of the coupling on small tori. Our method enables computations at arbitrary values of the bare coupling and lattice spacing with current quantum computers, simulators and tensor-network calculations, in regimes otherwise inaccessible.
Sannia, A.; Tacchino, F.; I. Giorgi Tavernelli, G. L.; Zambrini, R.
Engineered dissipation to mitigate barren plateaus Artículo de revista
En: NPJ/Quantum Information, vol. 10, iss. 81, 2024.
Resumen | Enlaces | BibTeX | Etiquetas: CSIC-4.7
@article{nokey,
title = {Engineered dissipation to mitigate barren plateaus},
author = { Sannia, A. and Tacchino, F. and Tavernelli, I. Giorgi, G.L. and Zambrini, R.},
url = {https://www.nature.com/articles/s41534-024-00875-0#citeas},
doi = {doi.org/10.1038/s41534-024-00875-0},
year = {2024},
date = {2024-09-04},
journal = {NPJ/Quantum Information},
volume = {10},
issue = {81},
abstract = {Variational quantum algorithms represent a powerful approach for solving optimization problems on noisy quantum computers, with a broad spectrum of potential applications ranging from chemistry to machine learning. However, their performances in practical implementations crucially depend on the effectiveness of quantum circuit training, which can be severely limited by phenomena such as barren plateaus. While, in general, dissipation is detrimental for quantum algorithms, and noise itself can actually induce barren plateaus, here we describe how the inclusion of properly engineered Markovian losses after each unitary quantum circuit layer allows for the trainability of quantum models. We identify the required form of the dissipation processes and establish that their optimization is efficient. We benchmark the generality of our proposal in both a synthetic and a practical quantum chemistry example, demonstrating its effectiveness and potential impact across different domains.},
keywords = {CSIC-4.7},
pubstate = {published},
tppubtype = {article}
}
Variational quantum algorithms represent a powerful approach for solving optimization problems on noisy quantum computers, with a broad spectrum of potential applications ranging from chemistry to machine learning. However, their performances in practical implementations crucially depend on the effectiveness of quantum circuit training, which can be severely limited by phenomena such as barren plateaus. While, in general, dissipation is detrimental for quantum algorithms, and noise itself can actually induce barren plateaus, here we describe how the inclusion of properly engineered Markovian losses after each unitary quantum circuit layer allows for the trainability of quantum models. We identify the required form of the dissipation processes and establish that their optimization is efficient. We benchmark the generality of our proposal in both a synthetic and a practical quantum chemistry example, demonstrating its effectiveness and potential impact across different domains.
deMarti iOlius, A.; Etxezarreta Martinez, I.; Roffe, J.; Etxezarreta Martinez, J.
An almost-linear time decoding algorithm for quantum LDPC codes under circuit-level noise Working paper
2024.
Resumen | Enlaces | BibTeX | Etiquetas: TECNUN
@workingpaper{nokey,
title = {An almost-linear time decoding algorithm for quantum LDPC codes under circuit-level noise},
author = {deMarti iOlius, A. and Etxezarreta Martinez, I. and Roffe, J. and Etxezarreta Martinez, J. },
url = {https://arxiv.org/abs/2409.01440},
doi = {doi.org/10.48550/arXiv.2409.01440 Focus to learn more},
year = {2024},
date = {2024-09-02},
urldate = {2024-09-02},
abstract = {Fault-tolerant quantum computers must be designed in conjunction with classical co-processors that decode quantum error correction measurement information in real-time. In this work, we introduce the belief propagation plus ordered Tanner forest (BP+OTF) algorithm as an almost-linear time decoder for quantum low-density parity-check codes. The OTF post-processing stage removes qubits from the decoding graph until it has a tree-like structure. Provided that the resultant loop-free OTF graph supports a subset of qubits that can generate the syndrome, BP decoding is then guaranteed to converge. To enhance performance under circuit-level noise, we introduce a technique for sparsifying detector error models. This method uses a transfer matrix to map soft information from the full detector graph to the sparsified graph, preserving critical error propagation information from the syndrome extraction circuit. Our BP+OTF implementation first applies standard BP to the full detector graph, followed by BP+OTF post-processing on the sparsified graph. Numerical simulations show that the BP+OTF decoder achieves logical error suppression within an order of magnitude of state-of-the-art inversion-based decoders while maintaining almost-linear runtime complexity across all stages.},
keywords = {TECNUN},
pubstate = {published},
tppubtype = {workingpaper}
}
Fault-tolerant quantum computers must be designed in conjunction with classical co-processors that decode quantum error correction measurement information in real-time. In this work, we introduce the belief propagation plus ordered Tanner forest (BP+OTF) algorithm as an almost-linear time decoder for quantum low-density parity-check codes. The OTF post-processing stage removes qubits from the decoding graph until it has a tree-like structure. Provided that the resultant loop-free OTF graph supports a subset of qubits that can generate the syndrome, BP decoding is then guaranteed to converge. To enhance performance under circuit-level noise, we introduce a technique for sparsifying detector error models. This method uses a transfer matrix to map soft information from the full detector graph to the sparsified graph, preserving critical error propagation information from the syndrome extraction circuit. Our BP+OTF implementation first applies standard BP to the full detector graph, followed by BP+OTF post-processing on the sparsified graph. Numerical simulations show that the BP+OTF decoder achieves logical error suppression within an order of magnitude of state-of-the-art inversion-based decoders while maintaining almost-linear runtime complexity across all stages.
Llorens, S.; Sentís, G.; Muñoz-Tapia, R.
Quantum multi-anomaly detection Artículo de revista
En: Quantum, vol. 8, pp. 1452, 2024.
Resumen | Enlaces | BibTeX | Etiquetas: UAB
@article{nokey,
title = {Quantum multi-anomaly detection},
author = {Llorens, S. and Sentís, G. and Muñoz-Tapia, R.},
url = {https://quantum-journal.org/papers/q-2024-08-28-1452/},
doi = {doi.org/10.22331/q-2024-08-28-1452},
year = {2024},
date = {2024-08-28},
urldate = {2024-08-28},
journal = {Quantum},
volume = {8},
pages = {1452},
abstract = {A source assumed to prepare a specified reference state sometimes prepares an anomalous one. We address the task of identifying these anomalous states in a series of
n preparations with k anomalies. We analyze the minimum-error protocol and the zero-error (unambiguous) protocol and obtain closed expressions for the success probability when both reference and anomalous states are known to the observer and anomalies can appear equally likely in any position of the preparation series. We find the solution using results from association schemes theory, thus establishing a connection between graph theory and quantum hypothesis testing. In particular, we use the Johnson association scheme which arises naturally from the Gram matrix of this problem. We also study the regime of large n and obtain the expression of the success probability that is non-vanishing. Finally, we address the case in which the observer is blind to the reference and the anomalous states. This scenario requires a universal protocol for which we prove that in the asymptotic limit, the success probability corresponds to the average of the known state scenario.},
keywords = {UAB},
pubstate = {published},
tppubtype = {article}
}
A source assumed to prepare a specified reference state sometimes prepares an anomalous one. We address the task of identifying these anomalous states in a series of
n preparations with k anomalies. We analyze the minimum-error protocol and the zero-error (unambiguous) protocol and obtain closed expressions for the success probability when both reference and anomalous states are known to the observer and anomalies can appear equally likely in any position of the preparation series. We find the solution using results from association schemes theory, thus establishing a connection between graph theory and quantum hypothesis testing. In particular, we use the Johnson association scheme which arises naturally from the Gram matrix of this problem. We also study the regime of large n and obtain the expression of the success probability that is non-vanishing. Finally, we address the case in which the observer is blind to the reference and the anomalous states. This scenario requires a universal protocol for which we prove that in the asymptotic limit, the success probability corresponds to the average of the known state scenario.
n preparations with k anomalies. We analyze the minimum-error protocol and the zero-error (unambiguous) protocol and obtain closed expressions for the success probability when both reference and anomalous states are known to the observer and anomalies can appear equally likely in any position of the preparation series. We find the solution using results from association schemes theory, thus establishing a connection between graph theory and quantum hypothesis testing. In particular, we use the Johnson association scheme which arises naturally from the Gram matrix of this problem. We also study the regime of large n and obtain the expression of the success probability that is non-vanishing. Finally, we address the case in which the observer is blind to the reference and the anomalous states. This scenario requires a universal protocol for which we prove that in the asymptotic limit, the success probability corresponds to the average of the known state scenario.
Cobos, J.; Locher, D. F.; Bermudez, A.; Müller, M.; Rico, E.
Noise-Aware Variational Eigensolvers: A Dissipative Route for Lattice Gauge Theories Artículo de revista
En: PRX Quantum, vol. 5, iss. 3, pp. 030340, 2024, ISSN: 2691-3399.
Resumen | Enlaces | BibTeX | Etiquetas: CSIC-4.8
@article{nokey,
title = {Noise-Aware Variational Eigensolvers: A Dissipative Route for Lattice Gauge Theories},
author = {Cobos, J. and Locher, D.F. and Bermudez, A. and Müller, M. and Rico, E. },
url = {https://journals.aps.org/prxquantum/abstract/10.1103/PRXQuantum.5.030340},
doi = {doi.org/10.1103/PRXQuantum.5.030340},
issn = {2691-3399},
year = {2024},
date = {2024-08-26},
urldate = {2024-08-26},
journal = {PRX Quantum},
volume = {5},
issue = {3},
pages = {030340},
abstract = {We propose a novel variational ansatz for the ground-state preparation of the lattice gauge theory (LGT) in quantum simulators. It combines dissipative and unitary operations in a completely deterministic scheme with a circuit depth that does not scale with the size of the considered lattice. We find that, with very few variational parameters, the ansatz can achieve precision in energy in both the confined and deconfined phase of the LGT. We benchmark our proposal against the unitary Hamiltonian variational ansatz showing a reduction in the required number of variational layers to achieve a target precision. After performing a finite-size scaling analysis, we show that our dissipative variational ansatz can predict accurate critical exponents without requiring a number of layers that scales with the system size, which is the standard situation for unitary ansätze. Furthermore, we investigate the performance of this variational eigensolver subject to circuit-level noise, determining variational error thresholds that fix the error rate below which it would be beneficial to increase the number of layers. In light of these quantities and for typical gate errors in current quantum processors, we provide a detailed assessment of the prospects of our scheme to explore the LGT on near-term devices.},
keywords = {CSIC-4.8},
pubstate = {published},
tppubtype = {article}
}
We propose a novel variational ansatz for the ground-state preparation of the lattice gauge theory (LGT) in quantum simulators. It combines dissipative and unitary operations in a completely deterministic scheme with a circuit depth that does not scale with the size of the considered lattice. We find that, with very few variational parameters, the ansatz can achieve precision in energy in both the confined and deconfined phase of the LGT. We benchmark our proposal against the unitary Hamiltonian variational ansatz showing a reduction in the required number of variational layers to achieve a target precision. After performing a finite-size scaling analysis, we show that our dissipative variational ansatz can predict accurate critical exponents without requiring a number of layers that scales with the system size, which is the standard situation for unitary ansätze. Furthermore, we investigate the performance of this variational eigensolver subject to circuit-level noise, determining variational error thresholds that fix the error rate below which it would be beneficial to increase the number of layers. In light of these quantities and for typical gate errors in current quantum processors, we provide a detailed assessment of the prospects of our scheme to explore the LGT on near-term devices.
Labay-Mora, A.; Fiorelli, E.; Zambrini, R.; Giorgi, G. L.
Theoretical framework for quantum associative memories Working paper
2024.
Resumen | Enlaces | BibTeX | Etiquetas: CSIC-4.7
@workingpaper{nokey,
title = {Theoretical framework for quantum associative memories},
author = {Labay-Mora, A. and Fiorelli, E. and Zambrini, R. and Giorgi, G.L. },
url = {https://arxiv.org/abs/2408.14272},
doi = {doi.org/10.48550/arXiv.2408.14272},
year = {2024},
date = {2024-08-26},
abstract = {Associative memory refers to the ability to relate a memory with an input and targets the restoration of corrupted patterns. It has been intensively studied in classical physical systems, as in neural networks where an attractor dynamics settles on stable solutions. Several extensions to the quantum domain have been recently reported, displaying different features. In this work, we develop a comprehensive framework for a quantum associative memory based on open quantum system dynamics, which allows us to compare existing models, identify the theoretical prerequisites for performing associative memory tasks, and extend it in different forms. The map that achieves an exponential increase in the number of stored patterns with respect to classical systems is derived. We establish the crucial role of symmetries and dissipation in the operation of quantum associative memory. Our theoretical analysis demonstrates the feasibility of addressing both quantum and classical patterns, orthogonal and non-orthogonal memories, stationary and metastable operating regimes, and measurement-based outputs. Finally, this opens up new avenues for practical applications in quantum computing and machine learning, such as quantum error correction or quantum memories.},
keywords = {CSIC-4.7},
pubstate = {published},
tppubtype = {workingpaper}
}
Associative memory refers to the ability to relate a memory with an input and targets the restoration of corrupted patterns. It has been intensively studied in classical physical systems, as in neural networks where an attractor dynamics settles on stable solutions. Several extensions to the quantum domain have been recently reported, displaying different features. In this work, we develop a comprehensive framework for a quantum associative memory based on open quantum system dynamics, which allows us to compare existing models, identify the theoretical prerequisites for performing associative memory tasks, and extend it in different forms. The map that achieves an exponential increase in the number of stored patterns with respect to classical systems is derived. We establish the crucial role of symmetries and dissipation in the operation of quantum associative memory. Our theoretical analysis demonstrates the feasibility of addressing both quantum and classical patterns, orthogonal and non-orthogonal memories, stationary and metastable operating regimes, and measurement-based outputs. Finally, this opens up new avenues for practical applications in quantum computing and machine learning, such as quantum error correction or quantum memories.
Security of quantum position-verification limits Hamiltonian simulation via holography Artículo de revista
En: Journal of High Energy Physics, vol. 2024, iss. 8, no 152, 2024.
Resumen | Enlaces | BibTeX | Etiquetas: UCM-4.2
@article{nokey,
title = {Security of quantum position-verification limits Hamiltonian simulation via holography},
url = {https://link.springer.com/article/10.1007/JHEP08(2024)152},
doi = {doi.org/10.1007/JHEP08(2024)152},
year = {2024},
date = {2024-08-20},
journal = {Journal of High Energy Physics},
volume = {2024},
number = {152},
issue = {8},
abstract = {We investigate the link between quantum position-verification (QPV) and holography established in [1] using holographic quantum error correcting codes as toy models. By inserting the “temporal” scaling of the AdS metric by hand via the bulk Hamiltonian interaction strength, we recover a toy model with consistent causality structure. This leads to an interesting implication between two topics in quantum information: if position-based verification is secure against attacks with small entanglement then there are new fundamental lower bounds for resources required for one Hamiltonian to simulate another.},
keywords = {UCM-4.2},
pubstate = {published},
tppubtype = {article}
}
We investigate the link between quantum position-verification (QPV) and holography established in [1] using holographic quantum error correcting codes as toy models. By inserting the “temporal” scaling of the AdS metric by hand via the bulk Hamiltonian interaction strength, we recover a toy model with consistent causality structure. This leads to an interesting implication between two topics in quantum information: if position-based verification is secure against attacks with small entanglement then there are new fundamental lower bounds for resources required for one Hamiltonian to simulate another.
Giordano, S.; Martin-Delgado, M. A.
Quantum Algorithm for Testing Graph Completeness Working paper
2024.
Resumen | Enlaces | BibTeX | Etiquetas: UCM-4.3
@workingpaper{nokey,
title = {Quantum Algorithm for Testing Graph Completeness},
author = {Giordano, S. and Martin-Delgado, M.A.
},
url = {https://arxiv.org/abs/2407.20069},
doi = {doi.org/10.48550/arXiv.2407.20069},
year = {2024},
date = {2024-08-16},
urldate = {2024-08-16},
abstract = {Testing graph completeness is a critical problem in computer science and network theory. Leveraging quantum computation, we present an efficient algorithm using the Szegedy quantum walk and quantum phase estimation (QPE). Our algorithm, which takes the number of nodes and the adjacency matrix as input, constructs a quantum walk operator and applies QPE to estimate its eigenvalues. These eigenvalues reveal the graph's structural properties, enabling us to determine its completeness. We establish a relationship between the number of nodes in a complete graph and the number of marked nodes, optimizing the success probability and running time. The time complexity of our algorithm is , where is the number of nodes of the graph. offering a clear quantum advantage over classical methods. This approach is useful in network structure analysis, evaluating classical routing algorithms, and assessing systems based on pairwise comparisons.},
keywords = {UCM-4.3},
pubstate = {published},
tppubtype = {workingpaper}
}
Testing graph completeness is a critical problem in computer science and network theory. Leveraging quantum computation, we present an efficient algorithm using the Szegedy quantum walk and quantum phase estimation (QPE). Our algorithm, which takes the number of nodes and the adjacency matrix as input, constructs a quantum walk operator and applies QPE to estimate its eigenvalues. These eigenvalues reveal the graph's structural properties, enabling us to determine its completeness. We establish a relationship between the number of nodes in a complete graph and the number of marked nodes, optimizing the success probability and running time. The time complexity of our algorithm is , where is the number of nodes of the graph. offering a clear quantum advantage over classical methods. This approach is useful in network structure analysis, evaluating classical routing algorithms, and assessing systems based on pairwise comparisons.
Xu, T. N.; Ding, Y.; Martín-Guerrero, J. D.; Chen, X.
Robust two-qubit gate with reinforcement learning and dropout Artículo de revista
En: Physical Review A, vol. 110, iss. 3, 2024.
Resumen | Enlaces | BibTeX | Etiquetas: UV
@article{nokey,
title = {Robust two-qubit gate with reinforcement learning and dropout},
author = {Xu, T.N. and Ding, Y. and Martín-Guerrero, J.D. and Chen, X.},
url = {https://journals.aps.org/pra/abstract/10.1103/PhysRevA.110.032614},
doi = {doi.org/10.1103/PhysRevA.110.032614},
year = {2024},
date = {2024-08-13},
urldate = {2024-08-13},
journal = {Physical Review A},
volume = {110},
issue = {3},
abstract = {In the realm of quantum control, reinforcement learning, a prominent branch of machine learning, emerges as a competitive candidate for computer-assisted optimal experiment design. This paper investigates the extent to which guidance from human experts is necessary for effectively implementing reinforcement learning in the design of quantum control protocols. Specifically, our focus lies on engineering a robust two-qubit gate, utilizing a combination of analytical solutions as prior knowledge and techniques from computer science. Through thorough benchmarking of various models, we identify dropout—a widely used method for mitigating overfitting in machine learning—as a particularly robust approach. Our findings demonstrate the potential of integrating computer science concepts to propel the development of advanced quantum technologies.},
howpublished = {Preprint},
keywords = {UV},
pubstate = {published},
tppubtype = {article}
}
In the realm of quantum control, reinforcement learning, a prominent branch of machine learning, emerges as a competitive candidate for computer-assisted optimal experiment design. This paper investigates the extent to which guidance from human experts is necessary for effectively implementing reinforcement learning in the design of quantum control protocols. Specifically, our focus lies on engineering a robust two-qubit gate, utilizing a combination of analytical solutions as prior knowledge and techniques from computer science. Through thorough benchmarking of various models, we identify dropout—a widely used method for mitigating overfitting in machine learning—as a particularly robust approach. Our findings demonstrate the potential of integrating computer science concepts to propel the development of advanced quantum technologies.
Cabot, A.; Giorgi, G. L.; Zambrini, R.
Nonequilibrium transition between dissipative time crystals Artículo de revista
En: PRX Quantum, vol. 5, iss. 3, no 30325, 2024.
Resumen | Enlaces | BibTeX | Etiquetas: CSIC-4.7
@article{nokey,
title = {Nonequilibrium transition between dissipative time crystals},
author = {Cabot, A. and Giorgi, G.L. and Zambrini, R.},
url = {https://journals.aps.org/prxquantum/abstract/10.1103/PRXQuantum.5.030325},
doi = {doi.org/10.1103/PRXQuantum.5.030325},
year = {2024},
date = {2024-08-06},
journal = {PRX Quantum},
volume = {5},
number = {30325},
issue = {3},
abstract = {We show a dissipative phase transition in a driven nonlinear quantum oscillator in which a discrete time-translation symmetry is spontaneously broken in two different ways. The corresponding regimes display either discrete or incommensurate time-crystal order, which we analyze numerically and analytically beyond the classical limit, addressing observable dynamics, phenomenology in different (laboratory and rotating) frames, Liouvillian spectral features, and quantum fluctuations. Via an effective semiclassical description, we show that phase diffusion dominates in the incommensurate time crystal (or continuous time crystal in the rotating frame), which manifests as a band of eigenmodes with a lifetime growing linearly with the mean-field excitation number. Instead, in the discrete time-crystal phase, the leading fluctuation process corresponds to quantum activation with a single mode that has an exponentially growing lifetime. Interestingly, the transition between these two regimes manifests itself already in the quantum regime as a spectral singularity, namely, as an exceptional point mediating between phase diffusion and quantum activation. Finally, we discuss this transition between different time-crystal orders in the context of synchronization phenomena.},
keywords = {CSIC-4.7},
pubstate = {published},
tppubtype = {article}
}
We show a dissipative phase transition in a driven nonlinear quantum oscillator in which a discrete time-translation symmetry is spontaneously broken in two different ways. The corresponding regimes display either discrete or incommensurate time-crystal order, which we analyze numerically and analytically beyond the classical limit, addressing observable dynamics, phenomenology in different (laboratory and rotating) frames, Liouvillian spectral features, and quantum fluctuations. Via an effective semiclassical description, we show that phase diffusion dominates in the incommensurate time crystal (or continuous time crystal in the rotating frame), which manifests as a band of eigenmodes with a lifetime growing linearly with the mean-field excitation number. Instead, in the discrete time-crystal phase, the leading fluctuation process corresponds to quantum activation with a single mode that has an exponentially growing lifetime. Interestingly, the transition between these two regimes manifests itself already in the quantum regime as a spectral singularity, namely, as an exceptional point mediating between phase diffusion and quantum activation. Finally, we discuss this transition between different time-crystal orders in the context of synchronization phenomena.
Ferreiro-Vélez, J.; Iriarte-Zendoia, I.; Ban, Y.; Chen, Xi.
Shortcuts for Adiabatic and Variational Algorithms in Molecular Simulation Working paper
Preprint, 2024.
Resumen | Enlaces | BibTeX | Etiquetas: UPV/EHU
@workingpaper{nokey,
title = {Shortcuts for Adiabatic and Variational Algorithms in Molecular Simulation},
author = {Ferreiro-Vélez, J. and Iriarte-Zendoia, I. and Ban, Y. and Chen, Xi. },
url = {https://arxiv.org/pdf/2407.20957},
doi = {doi.org/10.48550/arXiv.2407.20957},
year = {2024},
date = {2024-07-30},
urldate = {2024-07-30},
abstract = {Quantum algorithms are prominent in the pursuit of achieving quantum advantage in various computational tasks. However, addressing challenges, such as limited qubit coherence and high error rate in near-term devices, requires extensive efforts. In this paper, we present a substantial stride in quantum chemistry by integrating shortcuts-to-adiabaticity techniques into adiabatic and variational algorithms for calculating the molecular ground state. Our approach includes the counter-diabatic driving that accelerates adiabatic evolution by mitigating adiabatic errors. Additionally, we introduce the counter-diabatic terms as the adiabatic gauge ansatz for the variational quantum eigensolver, which exhibits favorable convergence properties with a fewer number of parameters, thereby reducing the circuit depth. Our approach achieves comparable accuracy to other established ansatzes, while enhancing the potential for applications in material science, drug discovery, and molecular simulations.},
howpublished = {Preprint},
keywords = {UPV/EHU},
pubstate = {published},
tppubtype = {workingpaper}
}
Quantum algorithms are prominent in the pursuit of achieving quantum advantage in various computational tasks. However, addressing challenges, such as limited qubit coherence and high error rate in near-term devices, requires extensive efforts. In this paper, we present a substantial stride in quantum chemistry by integrating shortcuts-to-adiabaticity techniques into adiabatic and variational algorithms for calculating the molecular ground state. Our approach includes the counter-diabatic driving that accelerates adiabatic evolution by mitigating adiabatic errors. Additionally, we introduce the counter-diabatic terms as the adiabatic gauge ansatz for the variational quantum eigensolver, which exhibits favorable convergence properties with a fewer number of parameters, thereby reducing the circuit depth. Our approach achieves comparable accuracy to other established ansatzes, while enhancing the potential for applications in material science, drug discovery, and molecular simulations.
Florido-Llinàs, M.; Alhambra, A. M.; Pérez-García, D.; Cirac, J. I.
Regular language quantum states Working paper
2024.
Resumen | Enlaces | BibTeX | Etiquetas: UCM-4.2
@workingpaper{nokey,
title = {Regular language quantum states},
author = {Florido-Llinàs, M. and Alhambra, A.M. and Pérez-García, D. and Cirac, J.I. },
url = {https://arxiv.org/abs/2407.17641},
doi = {doi.org/10.48550/arXiv.2407.17641},
year = {2024},
date = {2024-07-24},
urldate = {2024-07-24},
abstract = {We introduce regular language states, a family of quantum many-body states. They are built from a special class of formal languages, called regular, which has been thoroughly studied in the field of computer science. They can be understood as the superposition of all the words in a regular language and encompass physically relevant states such as the GHZ-, W- or Dicke-states. By leveraging the theory of regular languages, we develop a theoretical framework to describe them. First, we express them in terms of matrix product states, providing efficient criteria to recognize them. We then develop a canonical form which allows us to formulate a fundamental theorem for the equivalence of regular language states, including under local unitary operations. We also exploit the theory of tensor networks to find an efficient criterion to determine when regular languages are shift-invariant.
},
keywords = {UCM-4.2},
pubstate = {published},
tppubtype = {workingpaper}
}
We introduce regular language states, a family of quantum many-body states. They are built from a special class of formal languages, called regular, which has been thoroughly studied in the field of computer science. They can be understood as the superposition of all the words in a regular language and encompass physically relevant states such as the GHZ-, W- or Dicke-states. By leveraging the theory of regular languages, we develop a theoretical framework to describe them. First, we express them in terms of matrix product states, providing efficient criteria to recognize them. We then develop a canonical form which allows us to formulate a fundamental theorem for the equivalence of regular language states, including under local unitary operations. We also exploit the theory of tensor networks to find an efficient criterion to determine when regular languages are shift-invariant.
Nokkala, J.; Giorgi, G. L.; Zambrini, R.
Retrieving past quantum features with deep hybrid classical-quantum reservoir computing Artículo de revista
En: Machine Learning: Science and Technology, vol. 5, 2024.
Resumen | Enlaces | BibTeX | Etiquetas: CSIC-4.7
@article{nokey,
title = {Retrieving past quantum features with deep hybrid classical-quantum reservoir computing},
author = {Nokkala, J. and Giorgi, G.L. and Zambrini, R. },
url = {https://iopscience.iop.org/article/10.1088/2632-2153/ad5f12},
doi = {10.1088/2632-2153/ad5f12},
year = {2024},
date = {2024-07-19},
journal = {Machine Learning: Science and Technology},
volume = {5},
abstract = {Machine learning techniques have achieved impressive results in recent years and the possibility of harnessing the power of quantum physics opens new promising avenues to speed up classical learning methods. Rather than viewing classical and quantum approaches as exclusive alternatives, their integration into hybrid designs has gathered increasing interest, as seen in variational quantum algorithms, quantum circuit learning, and kernel methods. Here we introduce deep hybrid classical-quantum reservoir computing for temporal processing of quantum states where information about, for instance, the entanglement or the purity of past input states can be extracted via a single-step measurement. We find that the hybrid setup cascading two reservoirs not only inherits the strengths of both of its constituents but is even more than just the sum of its parts, outperforming comparable non-hybrid alternatives. The quantum layer is within reach of state-of-the-art multimode quantum optical platforms while the classical layer can be implemented in silico.},
keywords = {CSIC-4.7},
pubstate = {published},
tppubtype = {article}
}
Machine learning techniques have achieved impressive results in recent years and the possibility of harnessing the power of quantum physics opens new promising avenues to speed up classical learning methods. Rather than viewing classical and quantum approaches as exclusive alternatives, their integration into hybrid designs has gathered increasing interest, as seen in variational quantum algorithms, quantum circuit learning, and kernel methods. Here we introduce deep hybrid classical-quantum reservoir computing for temporal processing of quantum states where information about, for instance, the entanglement or the purity of past input states can be extracted via a single-step measurement. We find that the hybrid setup cascading two reservoirs not only inherits the strengths of both of its constituents but is even more than just the sum of its parts, outperforming comparable non-hybrid alternatives. The quantum layer is within reach of state-of-the-art multimode quantum optical platforms while the classical layer can be implemented in silico.
Acuaviva, A.; Aguirre, D.; Peña, R.; Sanz, M.
Benchmarking Quantum Computers: Towards a Standard Performance Evaluation Approach Working paper
2024.
Resumen | Enlaces | BibTeX | Etiquetas: UPV/EHU
@workingpaper{nokey,
title = {Benchmarking Quantum Computers: Towards a Standard Performance Evaluation Approach},
author = {Acuaviva, A. and Aguirre, D. and Peña, R. and Sanz, M. },
url = {https://arxiv.org/abs/2407.10941},
doi = {doi.org/10.48550/arXiv.2407.10941},
year = {2024},
date = {2024-07-17},
urldate = {2024-07-17},
abstract = {The technological development of increasingly larger quantum processors on different quantum platforms raises the problem of how to fairly compare their performance, known as quantum benchmarking of quantum processors. This is a challenge that computer scientists have already faced when comparing classical processors, leading to the development of various mathematical tools to address it, but also to the identification of the limits of this problem. In this work, we briefly review the most important aspects of both classical processor benchmarks and the metrics comprising them, providing precise definitions and analyzing the quality attributes that they should exhibit. Subsequently, we analyze the intrinsic properties that characterize the paradigm of quantum computing and hinder the naive transfer of strategies from classical benchmarking. However, we can still leverage some of the lessons learned such as the quality attributes of a textit{good} benchmark. Additionally, we review some of the most important metrics and benchmarks for quantum processors proposed in the literature, assessing what quality attributes they fulfill. Finally, we propose general guidelines for quantum benchmarking. These guidelines aim to pave the way for establishing a roadmap towards standardizing the performance evaluation of quantum devices, ultimately leading to the creation of an organization akin to the Standard Performance Evaluation Corporation (SPEC).},
keywords = {UPV/EHU},
pubstate = {published},
tppubtype = {workingpaper}
}
The technological development of increasingly larger quantum processors on different quantum platforms raises the problem of how to fairly compare their performance, known as quantum benchmarking of quantum processors. This is a challenge that computer scientists have already faced when comparing classical processors, leading to the development of various mathematical tools to address it, but also to the identification of the limits of this problem. In this work, we briefly review the most important aspects of both classical processor benchmarks and the metrics comprising them, providing precise definitions and analyzing the quality attributes that they should exhibit. Subsequently, we analyze the intrinsic properties that characterize the paradigm of quantum computing and hinder the naive transfer of strategies from classical benchmarking. However, we can still leverage some of the lessons learned such as the quality attributes of a textit{good} benchmark. Additionally, we review some of the most important metrics and benchmarks for quantum processors proposed in the literature, assessing what quality attributes they fulfill. Finally, we propose general guidelines for quantum benchmarking. These guidelines aim to pave the way for establishing a roadmap towards standardizing the performance evaluation of quantum devices, ultimately leading to the creation of an organization akin to the Standard Performance Evaluation Corporation (SPEC).
Mehrabankar, S.; García-March, M. A.; Almudéver, C. G.; Pérez, A.
Reducing the number of qubits in quantum simulations of one dimensional many-body Hamiltonians Working paper
2024.
Resumen | Enlaces | BibTeX | Etiquetas: UV
@workingpaper{nokey,
title = {Reducing the number of qubits in quantum simulations of one dimensional many-body Hamiltonians},
author = {Mehrabankar, S. and García-March, M.A. and Almudéver, C.G. and Pérez, A. },
url = {https://arxiv.org/abs/2308.01545},
doi = {doi.org/10.48550/arXiv.2505.03642},
year = {2024},
date = {2024-07-10},
urldate = {2024-07-10},
abstract = {We investigate the Ising and Heisenberg models using the Block Renormalization Group Method (BRGM), focusing on its behavior across different system sizes. The BRGM reduces the number of spins by a factor of 1/2 (1/3) for the Ising (Heisenberg) model, effectively preserving essential physical features of the model while using only a fraction of the spins. Through a comparative analysis, we demonstrate that as the system size increases, there is an exponential convergence between results obtained from the original and renormalized Ising Hamiltonians, provided the coupling constants are redefined accordingly. Remarkably, for a spin chain with 24 spins, all physical features, including magnetization, correlation function, and entanglement entropy, exhibit an exact correspondence with the results from the original Hamiltonian. The study of the Heisenberg model also shows this tendency, although complete convergence may appear for a size much larger than 24 spins, and is therefore beyond our computational capabilities. The success of BRGM in accurately characterizing the Ising model, even with a relatively small number of spins, underscores its robustness and utility in studying complex physical systems, and facilitates its simulation on current NISQ computers, where the available number of qubits is largely constrained.},
keywords = {UV},
pubstate = {published},
tppubtype = {workingpaper}
}
We investigate the Ising and Heisenberg models using the Block Renormalization Group Method (BRGM), focusing on its behavior across different system sizes. The BRGM reduces the number of spins by a factor of 1/2 (1/3) for the Ising (Heisenberg) model, effectively preserving essential physical features of the model while using only a fraction of the spins. Through a comparative analysis, we demonstrate that as the system size increases, there is an exponential convergence between results obtained from the original and renormalized Ising Hamiltonians, provided the coupling constants are redefined accordingly. Remarkably, for a spin chain with 24 spins, all physical features, including magnetization, correlation function, and entanglement entropy, exhibit an exact correspondence with the results from the original Hamiltonian. The study of the Heisenberg model also shows this tendency, although complete convergence may appear for a size much larger than 24 spins, and is therefore beyond our computational capabilities. The success of BRGM in accurately characterizing the Ising model, even with a relatively small number of spins, underscores its robustness and utility in studying complex physical systems, and facilitates its simulation on current NISQ computers, where the available number of qubits is largely constrained.
Becker, S.; Galke, N.; Salzmann, R.; Van Luijk, L.
Convergence rates for the Trotter-Kato splitting Working paper
2024.
Resumen | Enlaces | BibTeX | Etiquetas: UAB
@workingpaper{nokey,
title = {Convergence rates for the Trotter-Kato splitting},
author = {Becker, S. and Galke, N. and Salzmann, R. and Van Luijk, L.},
url = {https://arxiv.org/abs/2407.04045},
doi = {doi.org/10.48550/arXiv.2407.04045},
year = {2024},
date = {2024-07-04},
urldate = {2024-07-04},
abstract = {We study convergence rates of the Trotter–Kato splitting exp(A + L) = limₙ→∞ (exp(L/n) · exp(A/n))ⁿ in the strong operator topology. In the first part, we use complex interpolation theory to treat generators L and A of contraction semigroups on Banach spaces, with L relatively A-bounded. In the second part, we study unitary dynamics on Hilbert spaces and develop a new technique based on the concept of energy constraints. Our results provide a complete picture of the convergence rates for the Trotter splitting for all common types of Schrödinger and Dirac operators, including singular, confining and magnetic vector potentials, as well as molecular many-body Hamiltonians in dimension d = 3. Using the Brezis–Mironescu inequality, we derive convergence rates for the Schrödinger operator with potential V(x) = ±|x|^(–a). In each case, our conditions are fully explicit.
},
keywords = {UAB},
pubstate = {published},
tppubtype = {workingpaper}
}
We study convergence rates of the Trotter–Kato splitting exp(A + L) = limₙ→∞ (exp(L/n) · exp(A/n))ⁿ in the strong operator topology. In the first part, we use complex interpolation theory to treat generators L and A of contraction semigroups on Banach spaces, with L relatively A-bounded. In the second part, we study unitary dynamics on Hilbert spaces and develop a new technique based on the concept of energy constraints. Our results provide a complete picture of the convergence rates for the Trotter splitting for all common types of Schrödinger and Dirac operators, including singular, confining and magnetic vector potentials, as well as molecular many-body Hamiltonians in dimension d = 3. Using the Brezis–Mironescu inequality, we derive convergence rates for the Schrödinger operator with potential V(x) = ±|x|^(–a). In each case, our conditions are fully explicit.
D., Pérez-García; Santilli, L.; Tierz, M
Hawking-Page transition on a spin chain Artículo de revista
En: Physical Review Research, vol. 6, iss. 3, pp. 033007, 2024.
Resumen | Enlaces | BibTeX | Etiquetas: UCM-4.3
@article{nokey,
title = {Hawking-Page transition on a spin chain},
author = {Pérez-García D. and Santilli, L. and Tierz, M
},
url = {https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.6.033007},
doi = {doi.org/10.1103/PhysRevResearch.6.033007},
year = {2024},
date = {2024-07-01},
urldate = {2024-07-01},
journal = {Physical Review Research},
volume = {6},
issue = {3},
pages = {033007},
abstract = {The accessibility of the Hawking-Page transition in AdS5 through a one-dimensional (1D) Heisenberg spin chain is demonstrated. We use the random matrix formulation of the Loschmidt echo for a set of spin chains, and randomize the ferromagnetic spin interaction. It is shown that the thermal Loschmidt echo, when averaged, detects the predicted increase in entropy across the Hawking-Page transition. This suggests that a 1D spin chain exhibits characteristics of black hole physics in 4+1 dimensions. We show that this approach is equally applicable to free fermion systems with a general dispersion relation.},
keywords = {UCM-4.3},
pubstate = {published},
tppubtype = {article}
}
The accessibility of the Hawking-Page transition in AdS5 through a one-dimensional (1D) Heisenberg spin chain is demonstrated. We use the random matrix formulation of the Loschmidt echo for a set of spin chains, and randomize the ferromagnetic spin interaction. It is shown that the thermal Loschmidt echo, when averaged, detects the predicted increase in entropy across the Hawking-Page transition. This suggests that a 1D spin chain exhibits characteristics of black hole physics in 4+1 dimensions. We show that this approach is equally applicable to free fermion systems with a general dispersion relation.
Learning Quantum Processes Without Input Control Artículo de revista
En: PRX Quantum, vol. 5, iss. 2, no 20367, 2024.
Resumen | Enlaces | BibTeX | Etiquetas: UAB
@article{nokey,
title = {Learning Quantum Processes Without Input Control},
url = {https://journals.aps.org/prxquantum/abstract/10.1103/PRXQuantum.5.020367},
doi = {doi.org/10.1103/PRXQuantum.5.020367},
year = {2024},
date = {2024-06-27},
journal = {PRX Quantum},
volume = {5},
number = {20367},
issue = {2},
abstract = {We introduce a general statistical learning theory for processes that take as input a classical random variable and output a quantum state. Our setting is motivated by the practical situation in which one desires to learn a quantum process governed by classical parameters that are out of one’s control. This framework is applicable, for example, to the study of astronomical phenomena, disordered systems and biological processes not controlled by the observer. We provide an algorithm for learning with high probability in this setting with a finite amount of samples, even if the concept class is infinite. To do this, we review and adapt existing algorithms for shadow tomography and hypothesis selection, and combine their guarantees with the uniform convergence on the data of the loss functions of interest. As a byproduct, we obtain sufficient conditions for performing shadow tomography of classical-quantum states with a number of copies, which depends on the dimension of the quantum register, but not on the dimension of the classical one. We give concrete examples of processes that can be learned in this manner, based on quantum circuits or physically motivated classes, such as systems governed by Hamiltonians with random perturbations or data-dependent phase shifts.},
keywords = {UAB},
pubstate = {published},
tppubtype = {article}
}
We introduce a general statistical learning theory for processes that take as input a classical random variable and output a quantum state. Our setting is motivated by the practical situation in which one desires to learn a quantum process governed by classical parameters that are out of one’s control. This framework is applicable, for example, to the study of astronomical phenomena, disordered systems and biological processes not controlled by the observer. We provide an algorithm for learning with high probability in this setting with a finite amount of samples, even if the concept class is infinite. To do this, we review and adapt existing algorithms for shadow tomography and hypothesis selection, and combine their guarantees with the uniform convergence on the data of the loss functions of interest. As a byproduct, we obtain sufficient conditions for performing shadow tomography of classical-quantum states with a number of copies, which depends on the dimension of the quantum register, but not on the dimension of the classical one. We give concrete examples of processes that can be learned in this manner, based on quantum circuits or physically motivated classes, such as systems governed by Hamiltonians with random perturbations or data-dependent phase shifts.
Domanti, E. C.; Zappalà, D.; Bermudez, A.; Amico, L.
Floquet-Rydberg quantum simulator for confinement in gauge theories Artículo de revista
En: Physical Review Research, vol. 6, 2024.
Resumen | Enlaces | BibTeX | Etiquetas: CSIC-4.7
@article{nokey,
title = {Floquet-Rydberg quantum simulator for confinement in gauge theories},
author = {Domanti, E.C. and Zappalà, D. and Bermudez, A. and Amico, L. },
url = {https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.6.L022059},
doi = {doi.org/10.1103/PhysRevResearch.6.L022059},
year = {2024},
date = {2024-06-11},
journal = {Physical Review Research},
volume = {6},
abstract = {Recent advances in the field of quantum technologies have opened up the road for the realization of small-scale quantum simulators of lattice gauge theories which, among other goals, aim at improving our understanding on the nonperturbative mechanisms underlying the confinement of quarks. In this work, considering periodically driven arrays of Rydberg atoms in a tweezer ladder geometry, we devise a scalable Floquet scheme for the quantum simulation of the real-time dynamics in a LGT, in which hardcore bosons/spinless fermions are coupled to dynamical gauge fields. Resorting to an external magnetic field to tune the angular dependence of the Rydberg dipolar interactions, and by a suitable tuning of the driving parameters, we manage to suppress the main gauge-violating terms and show that an observation of gauge-invariant confinement dynamics in the Floquet-Rydberg setup is at reach of current experimental techniques. Depending on the lattice size, we present a thorough numerical test of the validity of this scheme using either exact diagonalization or matrix-product-state algorithms for the periodically modulated real-time dynamics.},
keywords = {CSIC-4.7},
pubstate = {published},
tppubtype = {article}
}
Recent advances in the field of quantum technologies have opened up the road for the realization of small-scale quantum simulators of lattice gauge theories which, among other goals, aim at improving our understanding on the nonperturbative mechanisms underlying the confinement of quarks. In this work, considering periodically driven arrays of Rydberg atoms in a tweezer ladder geometry, we devise a scalable Floquet scheme for the quantum simulation of the real-time dynamics in a LGT, in which hardcore bosons/spinless fermions are coupled to dynamical gauge fields. Resorting to an external magnetic field to tune the angular dependence of the Rydberg dipolar interactions, and by a suitable tuning of the driving parameters, we manage to suppress the main gauge-violating terms and show that an observation of gauge-invariant confinement dynamics in the Floquet-Rydberg setup is at reach of current experimental techniques. Depending on the lattice size, we present a thorough numerical test of the validity of this scheme using either exact diagonalization or matrix-product-state algorithms for the periodically modulated real-time dynamics.
Sáiz, Á.; Khalouf‑Rivera, J.; Arias, J. M.; Pérez‑Fernández, P.; Casado‑Pascual, J.
Quantum Phase Transitions in periodically quenched systems Artículo de revista
En: Quantum, vol. 8, pp. 1365, 2024.
Resumen | Enlaces | BibTeX | Etiquetas: US
@article{nokey,
title = {Quantum Phase Transitions in periodically quenched systems},
author = {Sáiz, Á. and Khalouf‑Rivera, J. and Arias, J. M. and Pérez‑Fernández, P. and Casado‑Pascual, J.},
url = {https://quantum-journal.org/papers/q-2024-06-11-1365/},
doi = {doi.org/10.22331/q-2024-06-11-1365},
year = {2024},
date = {2024-06-11},
urldate = {2024-06-11},
journal = {Quantum},
volume = {8},
pages = {1365},
abstract = {Quantum phase transitions encompass a variety of phenomena that occur in quantum systems exhibiting several possible symmetries. Traditionally, these transitions are explored by continuously varying a control parameter that connects two different symmetry configurations. Here we propose an alternative approach where the control parameter undergoes abrupt and time-periodic jumps between only two values. This approach yields results surprisingly similar to those obtained by the traditional one and may prove experimentally useful in situations where accessing the control parameter is challenging.},
keywords = {US},
pubstate = {published},
tppubtype = {article}
}
Quantum phase transitions encompass a variety of phenomena that occur in quantum systems exhibiting several possible symmetries. Traditionally, these transitions are explored by continuously varying a control parameter that connects two different symmetry configurations. Here we propose an alternative approach where the control parameter undergoes abrupt and time-periodic jumps between only two values. This approach yields results surprisingly similar to those obtained by the traditional one and may prove experimentally useful in situations where accessing the control parameter is challenging.
Pareja Monturiol, J. R.; Pérez-García, D.; Pozas-Kerstjens, A.
TensorKrowch: Smooth integration of tensor networks in machine learning Artículo de revista
En: Quantum, vol. 8, pp. 1364 , 2024.
Resumen | Enlaces | BibTeX | Etiquetas: UCM-4.2
@article{nokey,
title = {TensorKrowch: Smooth integration of tensor networks in machine learning},
author = {Pareja Monturiol, J.R. and Pérez-García, D. and Pozas-Kerstjens, A. },
url = {https://quantum-journal.org/papers/q-2024-06-11-1364/},
doi = {doi.org/10.22331/q-2024-06-11-1364},
year = {2024},
date = {2024-06-11},
journal = {Quantum},
volume = {8},
pages = {1364 },
abstract = {Tensor networks are factorizations of high-dimensional tensors into networks of smaller tensors. They have applications in physics and mathematics, and recently have been proposed as promising machine learning architectures. To ease the integration of tensor networks in machine learning pipelines, we introduce TensorKrowch, an open source Python library built on top of PyTorch. Providing a user-friendly interface, TensorKrowch allows users to construct any tensor network, train it, and integrate it as a layer in more intricate deep learning models. In this paper, we describe the main functionality and basic usage of TensorKrowch, and provide technical details on its building blocks and the optimizations performed to achieve efficient operation.},
keywords = {UCM-4.2},
pubstate = {published},
tppubtype = {article}
}
Tensor networks are factorizations of high-dimensional tensors into networks of smaller tensors. They have applications in physics and mathematics, and recently have been proposed as promising machine learning architectures. To ease the integration of tensor networks in machine learning pipelines, we introduce TensorKrowch, an open source Python library built on top of PyTorch. Providing a user-friendly interface, TensorKrowch allows users to construct any tensor network, train it, and integrate it as a layer in more intricate deep learning models. In this paper, we describe the main functionality and basic usage of TensorKrowch, and provide technical details on its building blocks and the optimizations performed to achieve efficient operation.
Aniello, P.; L’Innocente, S.; Mancini, S.; Parisi, V.; Svampa, I.; Winter, A.
Invariant measures on p-adic Lie groups: the p-adic quaternion algebra and the Haar integral on the p-adic rotation groups Artículo de revista
En: Letters in Mathematical Physics, vol. 114, iss. 3, no 78, 2024.
Resumen | Enlaces | BibTeX | Etiquetas: UAB
@article{nokey,
title = {Invariant measures on p-adic Lie groups: the p-adic quaternion algebra and the Haar integral on the p-adic rotation groups},
author = {Aniello, P. and L’Innocente, S. and Mancini, S. and Parisi, V. and Svampa, I. and Winter, A. },
url = {https://link.springer.com/article/10.1007/s11005-024-01826-8},
doi = {doi.org/10.1007/s11005-024-01826-8},
year = {2024},
date = {2024-06-06},
urldate = {2024-06-06},
journal = {Letters in Mathematical Physics},
volume = {114},
number = {78},
issue = {3},
abstract = {We provide a general expression of the Haar measure—that is, the essentially unique translation‑invariant measure—on a p‑adic Lie group. We then argue that this measure can be regarded as the measure naturally induced by the invariant volume form on the group, as it happens for a standard Lie group over the reals.
As an important application, we next consider the problem of determining the Haar measure on the p‑adic special orthogonal groups in dimension two, three, and four (for every prime number p). In particular, the Haar measure on SO(2, ℚₚ) is obtained by a direct application of our general formula. As for SO(3, ℚₚ) and SO(4, ℚₚ), instead, we show that Haar integrals on these two groups can conveniently be lifted to Haar integrals on certain p‑adic Lie groups from which the special orthogonal groups are obtained as quotients. This construction involves a suitable quaternion algebra over the field ℚₚ and is reminiscent of the quaternionic realization of the real rotation groups. Our results should pave the way to the development of harmonic analysis on the p‑adic special orthogonal groups, with potential applications in p‑adic quantum mechanics and in the recently proposed p‑adic quantum information theory.},
keywords = {UAB},
pubstate = {published},
tppubtype = {article}
}
We provide a general expression of the Haar measure—that is, the essentially unique translation‑invariant measure—on a p‑adic Lie group. We then argue that this measure can be regarded as the measure naturally induced by the invariant volume form on the group, as it happens for a standard Lie group over the reals.
As an important application, we next consider the problem of determining the Haar measure on the p‑adic special orthogonal groups in dimension two, three, and four (for every prime number p). In particular, the Haar measure on SO(2, ℚₚ) is obtained by a direct application of our general formula. As for SO(3, ℚₚ) and SO(4, ℚₚ), instead, we show that Haar integrals on these two groups can conveniently be lifted to Haar integrals on certain p‑adic Lie groups from which the special orthogonal groups are obtained as quotients. This construction involves a suitable quaternion algebra over the field ℚₚ and is reminiscent of the quaternionic realization of the real rotation groups. Our results should pave the way to the development of harmonic analysis on the p‑adic special orthogonal groups, with potential applications in p‑adic quantum mechanics and in the recently proposed p‑adic quantum information theory.
As an important application, we next consider the problem of determining the Haar measure on the p‑adic special orthogonal groups in dimension two, three, and four (for every prime number p). In particular, the Haar measure on SO(2, ℚₚ) is obtained by a direct application of our general formula. As for SO(3, ℚₚ) and SO(4, ℚₚ), instead, we show that Haar integrals on these two groups can conveniently be lifted to Haar integrals on certain p‑adic Lie groups from which the special orthogonal groups are obtained as quotients. This construction involves a suitable quaternion algebra over the field ℚₚ and is reminiscent of the quaternionic realization of the real rotation groups. Our results should pave the way to the development of harmonic analysis on the p‑adic special orthogonal groups, with potential applications in p‑adic quantum mechanics and in the recently proposed p‑adic quantum information theory.
Ding, Y.; Ban, Y.; Sanz, M.; Martín-Guerrero, J. D.; Chen, X.
Quantum Active Learning Working paper
2024.
Resumen | Enlaces | BibTeX | Etiquetas: UPV/EHU
@workingpaper{nokey,
title = {Quantum Active Learning},
author = {Ding, Y. and Ban, Y. and Sanz, M. and Martín-Guerrero, J.D. and Chen, X. },
url = {https://arxiv.org/abs/2405.18230},
doi = {doi.org/10.48550/arXiv.2405.18230},
year = {2024},
date = {2024-05-28},
urldate = {2024-05-28},
abstract = {Quantum machine learning, as an extension of classical machine learning that harnesses quantum mechanics, facilitates effiient learning from data encoded in quantum states. Training a quantum neural network typically demands a substantial labeled training set for supervised learning. Human annotators, often experts, provide labels for samples through additional experiments, adding to the training cost. To mitigate this expense, there is a quest for methods that maintain model performance over fully labeled datasets while requiring fewer labeled samples in practice, thereby extending few-shot learning to the quantum realm. Quantum active learning estimates the uncertainty of quantum data to select the most informative samples from a pool for labeling. Consequently, a QML model is supposed to accumulate maximal knowledge as the training set comprises labeled samples selected via sampling strategies. Notably, the QML models trained within the QAL framework are not restricted to specific types, enabling performance enhancement from the model architecture's perspective towards few-shot learning. Recognizing symmetry as a fundamental concept in physics ubiquitous across various domains, we leverage the symmetry inherent in quantum states induced by the embedding of classical data for model design. We employ an equivariant QNN capable of generalizing from fewer data with geometric priors. We benchmark the performance of QAL on two classification problems, observing both positive and negative results. QAL effectively trains the model, achieving performance comparable to that on fully labeled datasets by labeling less than 7% of the samples in the pool with unbiased sampling behavior. Furthermore, we elucidate the negative result of QAL being overtaken by random sampling baseline through miscellaneous numerical experiments. },
keywords = {UPV/EHU},
pubstate = {published},
tppubtype = {workingpaper}
}
Quantum machine learning, as an extension of classical machine learning that harnesses quantum mechanics, facilitates effiient learning from data encoded in quantum states. Training a quantum neural network typically demands a substantial labeled training set for supervised learning. Human annotators, often experts, provide labels for samples through additional experiments, adding to the training cost. To mitigate this expense, there is a quest for methods that maintain model performance over fully labeled datasets while requiring fewer labeled samples in practice, thereby extending few-shot learning to the quantum realm. Quantum active learning estimates the uncertainty of quantum data to select the most informative samples from a pool for labeling. Consequently, a QML model is supposed to accumulate maximal knowledge as the training set comprises labeled samples selected via sampling strategies. Notably, the QML models trained within the QAL framework are not restricted to specific types, enabling performance enhancement from the model architecture's perspective towards few-shot learning. Recognizing symmetry as a fundamental concept in physics ubiquitous across various domains, we leverage the symmetry inherent in quantum states induced by the embedding of classical data for model design. We employ an equivariant QNN capable of generalizing from fewer data with geometric priors. We benchmark the performance of QAL on two classification problems, observing both positive and negative results. QAL effectively trains the model, achieving performance comparable to that on fully labeled datasets by labeling less than 7% of the samples in the pool with unbiased sampling behavior. Furthermore, we elucidate the negative result of QAL being overtaken by random sampling baseline through miscellaneous numerical experiments.
Dastbasteh, R.; Etxezarreta Martinez, J.; A. deMarti iOlius Nemec, A. Crespo Bofill.
An Infinite class of quantum codes derived from duadic constacyclic codes Working paper
Preprint, 2024.
Resumen | Enlaces | BibTeX | Etiquetas: TECNUN
@workingpaper{nokey,
title = {An Infinite class of quantum codes derived from duadic constacyclic codes},
author = {Dastbasteh, R. and Etxezarreta Martinez, J. and Nemec, A. deMarti iOlius, A. Crespo Bofill.},
url = {https://link.springer.com/article/10.1007/s11128-025-04828-0},
doi = {doi.org/10.48550/arXiv.2312.06504},
year = {2024},
date = {2024-05-27},
urldate = {2024-05-27},
abstract = {We present a family of quantum stabilizer codes using the structure of duadic constacyclic codes over F4. Within this family, quantum codes can possess varying dimensions, and their minimum distances are lower bounded by a square root bound. For each fixed dimension, this allows us to construct an infinite sequence of binary quantum codes with a growing minimum distance. Additionally, we prove that this family of quantum codes includes an infinite subclass of degenerate codes. We also introduce a technique for extending splittings of duadic constacyclic codes, providing new insights into the minimum distance and minimum odd-like weight of specific duadic constacyclic codes. Finally, we provide numerical examples of some quantum codes with short lengths within this family.},
howpublished = {Preprint},
keywords = {TECNUN},
pubstate = {published},
tppubtype = {workingpaper}
}
We present a family of quantum stabilizer codes using the structure of duadic constacyclic codes over F4. Within this family, quantum codes can possess varying dimensions, and their minimum distances are lower bounded by a square root bound. For each fixed dimension, this allows us to construct an infinite sequence of binary quantum codes with a growing minimum distance. Additionally, we prove that this family of quantum codes includes an infinite subclass of degenerate codes. We also introduce a technique for extending splittings of duadic constacyclic codes, providing new insights into the minimum distance and minimum odd-like weight of specific duadic constacyclic codes. Finally, we provide numerical examples of some quantum codes with short lengths within this family.
Ruiz, R.; Sopena, A.; Hunter Gordon, M.; Sierra, G.; López, E.
The Bethe Ansatz as a Quantum Circuit Artículo de revista
En: Quantum, vol. 8, pp. 1356 , 2024.
Resumen | Enlaces | BibTeX | Etiquetas: CSIC-4.7
@article{nokey,
title = {The Bethe Ansatz as a Quantum Circuit},
author = {Ruiz, R. and Sopena, A. and Hunter Gordon, M. and Sierra, G. and López, E.},
url = {https://quantum-journal.org/papers/q-2024-05-23-1356/#},
doi = {doi.org/10.22331/q-2024-05-23-1356},
year = {2024},
date = {2024-05-23},
journal = {Quantum},
volume = {8},
pages = {1356 },
abstract = {The Bethe ansatz represents an analytical method enabling the exact solution of numerous models in condensed matter physics and statistical mechanics. When a global symmetry is present, the trial wavefunctions of the Bethe ansatz consist of plane wave superpositions. Previously, it has been shown that the Bethe ansatz can be recast as a deterministic quantum circuit. An analytical derivation of the quantum gates that form the circuit was lacking however. Here we present a comprehensive study of the transformation that brings the Bethe ansatz into a quantum circuit, which leads us to determine the analytical expression of the circuit gates. As a crucial step of the derivation, we present a simple set of diagrammatic rules that define a novel Matrix Product State network building Bethe wavefunctions. Remarkably, this provides a new perspective on the equivalence between the coordinate and algebraic versions of the Bethe ansatz.},
keywords = {CSIC-4.7},
pubstate = {published},
tppubtype = {article}
}
The Bethe ansatz represents an analytical method enabling the exact solution of numerous models in condensed matter physics and statistical mechanics. When a global symmetry is present, the trial wavefunctions of the Bethe ansatz consist of plane wave superpositions. Previously, it has been shown that the Bethe ansatz can be recast as a deterministic quantum circuit. An analytical derivation of the quantum gates that form the circuit was lacking however. Here we present a comprehensive study of the transformation that brings the Bethe ansatz into a quantum circuit, which leads us to determine the analytical expression of the circuit gates. As a crucial step of the derivation, we present a simple set of diagrammatic rules that define a novel Matrix Product State network building Bethe wavefunctions. Remarkably, this provides a new perspective on the equivalence between the coordinate and algebraic versions of the Bethe ansatz.
Ferrer-Sánchez, A.; Flores-Garrigós, C.; Hernani-Morales, C.; Orquín-Marqués, J. J.; Hegade, N. N.; A.G. Cadavid, Montalban; Solano, E.; Vives-Gilabert, Y.; Martín-Guerrero, J. D.
Physics-Informed Neural Networks for an optimal counterdiabatic quantum computation Artículo de revista
En: Machine Learning: Science and Technology, vol. 5, 2024.
Resumen | Enlaces | BibTeX | Etiquetas: UV
@article{nokey,
title = {Physics-Informed Neural Networks for an optimal counterdiabatic quantum computation},
author = {Ferrer-Sánchez, A. and Flores-Garrigós, C. and Hernani-Morales, C. and Orquín-Marqués, J.J. and Hegade, N.N. and Cadavid, A.G., Montalban, I. and Solano, E. and Vives-Gilabert, Y. and Martín-Guerrero, J.D. },
url = {https://iopscience.iop.org/article/10.1088/2632-2153/ad450f},
doi = {10.1088/2632-2153/ad450f},
year = {2024},
date = {2024-05-09},
urldate = {2023-09-08},
journal = {Machine Learning: Science and Technology},
volume = {5},
abstract = {We introduce a novel methodology that leverages the strength of Physics-Informed Neural Networks (PINNs) to address the counterdiabatic (CD) protocol in the optimization of quantum circuits comprised of systems with NQ qubits. The primary objective is to utilize physics-inspired deep learning techniques to accurately solve the time evolution of the different physical observables within the quantum system. To accomplish this objective, we embed the necessary physical information into an underlying neural network to effectively tackle the problem. In particular, we impose the hermiticity condition on all physical observables and make use of the principle of least action, guaranteeing the acquisition of the most appropriate counterdiabatic terms based on the underlying physics. The proposed approach offers a dependable alternative to address the CD driving problem, free from the constraints typically encountered in previous methodologies relying on classical numerical approximations. Our method provides a general framework to obtain optimal results from the physical observables relevant to the problem, including the external parameterization in time known as scheduling function, the gauge potential or operator involving the non-adiabatic terms, as well as the temporal evolution of the energy levels of the system, among others. The main applications of this methodology have been the H2 and LiH molecules, represented by a 2-qubit and 4-qubit systems employing the STO-3G basis. The presented results demonstrate the successful derivation of a desirable decomposition for the non-adiabatic terms, achieved through a linear combination utilizing Pauli operators. This attribute confers significant advantages to its practical implementation within quantum computing algorithms.},
keywords = {UV},
pubstate = {published},
tppubtype = {article}
}
We introduce a novel methodology that leverages the strength of Physics-Informed Neural Networks (PINNs) to address the counterdiabatic (CD) protocol in the optimization of quantum circuits comprised of systems with NQ qubits. The primary objective is to utilize physics-inspired deep learning techniques to accurately solve the time evolution of the different physical observables within the quantum system. To accomplish this objective, we embed the necessary physical information into an underlying neural network to effectively tackle the problem. In particular, we impose the hermiticity condition on all physical observables and make use of the principle of least action, guaranteeing the acquisition of the most appropriate counterdiabatic terms based on the underlying physics. The proposed approach offers a dependable alternative to address the CD driving problem, free from the constraints typically encountered in previous methodologies relying on classical numerical approximations. Our method provides a general framework to obtain optimal results from the physical observables relevant to the problem, including the external parameterization in time known as scheduling function, the gauge potential or operator involving the non-adiabatic terms, as well as the temporal evolution of the energy levels of the system, among others. The main applications of this methodology have been the H2 and LiH molecules, represented by a 2-qubit and 4-qubit systems employing the STO-3G basis. The presented results demonstrate the successful derivation of a desirable decomposition for the non-adiabatic terms, achieved through a linear combination utilizing Pauli operators. This attribute confers significant advantages to its practical implementation within quantum computing algorithms.
García-Ramos, J. E.; Sáiz, A.; Arias, J. M.; Lamata, L.; Pérez Fernández, P.
Nuclear Physics in the Era of Quantum Computing and Quantum Machine Learning Artículo de revista
En: Advanced Quantum Technologies, vol. 6, iss. 1, 2024.
Resumen | Enlaces | BibTeX | Etiquetas: US
@article{nokey,
title = {Nuclear Physics in the Era of Quantum Computing and Quantum Machine Learning},
author = {García-Ramos, J.E. and Sáiz, A. and Arias, J.M. and Lamata, L. and Pérez Fernández, P. },
url = {https://advanced.onlinelibrary.wiley.com/doi/10.1002/qute.202300219},
doi = {doi.org/10.1002/qute.202300219},
year = {2024},
date = {2024-05-03},
journal = {Advanced Quantum Technologies},
volume = {6},
issue = {1},
abstract = {In this paper, the application of quantum simulations and quantum machine learning is explored to solve problems in low-energy nuclear physics. The use of quantum computing to address nuclear physics problems is still in its infancy, and particularly, the application of quantum machine learning (QML) in the realm of low-energy nuclear physics is almost nonexistent. Three specific examples are presented where the utilization of quantum computing and QML provides, or can potentially provide in the future, a computational advantage: i) determining the phase/shape in schematic nuclear models, ii) calculating the ground state energy of a nuclear shell model-type Hamiltonian, and iii) identifying particles or determining trajectories in nuclear physics experiments.},
keywords = {US},
pubstate = {published},
tppubtype = {article}
}
In this paper, the application of quantum simulations and quantum machine learning is explored to solve problems in low-energy nuclear physics. The use of quantum computing to address nuclear physics problems is still in its infancy, and particularly, the application of quantum machine learning (QML) in the realm of low-energy nuclear physics is almost nonexistent. Three specific examples are presented where the utilization of quantum computing and QML provides, or can potentially provide in the future, a computational advantage: i) determining the phase/shape in schematic nuclear models, ii) calculating the ground state energy of a nuclear shell model-type Hamiltonian, and iii) identifying particles or determining trajectories in nuclear physics experiments.
Ferrer-Sánchez, A.; J.D. Ruiz de Austri-Bazan Martín-Guerrero, R.; Torres-Forné, A.; Font, J. A.
Gradient-annihilated PINNs for solving Riemann problems: Application to relativistic hydrodynamics Artículo de revista
En: Computer Methods in Applied Mechanics and Engineering, vol. 424, 2024.
Resumen | Enlaces | BibTeX | Etiquetas: UV
@article{nokey,
title = {Gradient-annihilated PINNs for solving Riemann problems: Application to relativistic hydrodynamics},
author = {Ferrer-Sánchez, A. and Martín-Guerrero, J.D. Ruiz de Austri-Bazan, R. and Torres-Forné, A. and Font, J.A. },
url = {https://www.sciencedirect.com/science/article/pii/S0045782524001622?via%3Dihub},
doi = {doi.org/10.1016/j.cma.2024.116906},
year = {2024},
date = {2024-05-01},
journal = {Computer Methods in Applied Mechanics and Engineering},
volume = {424},
abstract = {We present a novel methodology based on Physics-Informed Neural Networks (PINNs) for solving systems of partial differential equations admitting discontinuous solutions. Our method, called Gradient-Annihilated PINNs (GA-PINNs), introduces a modified loss function that forces the model to partially ignore high-gradients in the physical variables, achieved by introducing a suitable weighting function. The method relies on a set of hyperparameters that control how gradients are treated in the physical loss. The performance of our methodology is demonstrated by solving Riemann problems in special relativistic hydrodynamics, extending earlier studies with PINNs in the context of the classical Euler equations. The solutions obtained with the GA-PINN model correctly describe the propagation speeds of discontinuities and sharply capture the associated jumps. We use the relative 𝓁² error to compare our results with the exact solution of special relativistic Riemann problems, used as the reference “ground truth”, and with the corresponding error obtained with a second-order, central, shock-capturing scheme. In all problems investigated, the accuracy reached by the GA-PINN model is comparable to that obtained with a shock-capturing scheme, achieving a performance superior to that of the baseline PINN algorithm in general. An additional benefit worth stressing is that our PINN-based approach sidesteps the costly recovery of the primitive variables from the state vector of conserved variables, a well-known drawback of grid-based solutions of the relativistic hydrodynamics equations. Due to its inherent generality and its ability to handle steep gradients, the GA-PINN methodology discussed in this paper could be a valuable tool to model relativistic flows in astrophysics and particle physics, characterized by the prevalence of discontinuous solutions.},
keywords = {UV},
pubstate = {published},
tppubtype = {article}
}
We present a novel methodology based on Physics-Informed Neural Networks (PINNs) for solving systems of partial differential equations admitting discontinuous solutions. Our method, called Gradient-Annihilated PINNs (GA-PINNs), introduces a modified loss function that forces the model to partially ignore high-gradients in the physical variables, achieved by introducing a suitable weighting function. The method relies on a set of hyperparameters that control how gradients are treated in the physical loss. The performance of our methodology is demonstrated by solving Riemann problems in special relativistic hydrodynamics, extending earlier studies with PINNs in the context of the classical Euler equations. The solutions obtained with the GA-PINN model correctly describe the propagation speeds of discontinuities and sharply capture the associated jumps. We use the relative 𝓁² error to compare our results with the exact solution of special relativistic Riemann problems, used as the reference “ground truth”, and with the corresponding error obtained with a second-order, central, shock-capturing scheme. In all problems investigated, the accuracy reached by the GA-PINN model is comparable to that obtained with a shock-capturing scheme, achieving a performance superior to that of the baseline PINN algorithm in general. An additional benefit worth stressing is that our PINN-based approach sidesteps the costly recovery of the primitive variables from the state vector of conserved variables, a well-known drawback of grid-based solutions of the relativistic hydrodynamics equations. Due to its inherent generality and its ability to handle steep gradients, the GA-PINN methodology discussed in this paper could be a valuable tool to model relativistic flows in astrophysics and particle physics, characterized by the prevalence of discontinuous solutions.
Gonzalez-Raya, T.; Pirandola, S.; Sanz, M.
Satellite-based entanglement distribution and quantum teleportation with continuous variables Artículo de revista
En: Communications Physics, vol. 7, no 126, 2024, ISBN: 2399-3650.
Resumen | Enlaces | BibTeX | Etiquetas: UPV/EHU
@article{nokey,
title = {Satellite-based entanglement distribution and quantum teleportation with continuous variables},
author = {Gonzalez-Raya, T. and Pirandola, S. and Sanz, M. },
url = {https://www.nature.com/articles/s42005-024-01612-x.pdf},
doi = {doi.org/10.1038/s42005-024-01612-x},
isbn = {2399-3650},
year = {2024},
date = {2024-04-11},
journal = {Communications Physics},
volume = {7},
number = {126},
abstract = {Advances in satellite quantum communications aim at reshaping the global telecommunication network by increasing the security of the transferred information. Here, we study the effects of atmospheric turbulence in continuous-variable entanglement distribution and quantum teleportation in the optical regime between a ground station and a satellite. More specifically, we study the degradation of entanglement due to various error sources in the distribution, namely, diffraction, atmospheric attenuation, turbulence, and detector inefficiency, in both downlink and uplink scenarios. As the fidelity of a quantum teleportation protocol using these distributed entangled resources is not sufficient, we include an intermediate station for either state generation, or beam refocusing, in order to reduce the effects of atmospheric turbulence and diffraction, respectively. The results show the feasibility of free-space entanglement distribution and quantum teleportation in downlink paths up to the LEO region, but also in uplink paths with the help of the intermediate station. Finally, we complete the study with microwave-optical comparison in bad weather situations, and with the study of horizontal paths in ground-to-ground and inter-satellite quantum communication.},
keywords = {UPV/EHU},
pubstate = {published},
tppubtype = {article}
}
Advances in satellite quantum communications aim at reshaping the global telecommunication network by increasing the security of the transferred information. Here, we study the effects of atmospheric turbulence in continuous-variable entanglement distribution and quantum teleportation in the optical regime between a ground station and a satellite. More specifically, we study the degradation of entanglement due to various error sources in the distribution, namely, diffraction, atmospheric attenuation, turbulence, and detector inefficiency, in both downlink and uplink scenarios. As the fidelity of a quantum teleportation protocol using these distributed entangled resources is not sufficient, we include an intermediate station for either state generation, or beam refocusing, in order to reduce the effects of atmospheric turbulence and diffraction, respectively. The results show the feasibility of free-space entanglement distribution and quantum teleportation in downlink paths up to the LEO region, but also in uplink paths with the help of the intermediate station. Finally, we complete the study with microwave-optical comparison in bad weather situations, and with the study of horizontal paths in ground-to-ground and inter-satellite quantum communication.
Martínez-Peña, R.; Soriano, M. C.; Zambrini, R.
Quantum fidelity kernel with a trapped-ion simulation platform Artículo de revista
En: Physical Review A, vol. 109, iss. 4, 2024, ISSN: 2469-9926.
Resumen | Enlaces | BibTeX | Etiquetas: CSIC-4.7
@article{nokey,
title = {Quantum fidelity kernel with a trapped-ion simulation platform},
author = {Martínez-Peña, R. and Soriano, M.C. and Zambrini, R.
},
url = {https://journals.aps.org/pra/abstract/10.1103/PhysRevA.109.042612},
doi = {10.1103/PhysRevA.109.042612},
issn = {2469-9926},
year = {2024},
date = {2024-04-08},
urldate = {2024-04-08},
journal = {Physical Review A},
volume = {109},
issue = {4},
abstract = {Quantum kernel methods leverage a kernel function computed by embedding input information into the Hilbert space of a quantum system. However, large Hilbert spaces can hinder generalization capability, and the scalability of quantum kernels becomes an issue. To overcome these challenges, various strategies under the concept of inductive bias have been proposed. Bandwidth optimization is a promising approach that can be implemented using quantum simulation platforms. We propose trapped-ion simulation platforms as a means to compute quantum kernels, filling a gap in the previous literature and demonstrating their effectiveness for binary classification tasks. We compare the performance of the proposed method with an optimized classical kernel and evaluate the robustness of the quantum kernel against noise. The results show that ion trap platforms are well-suited for quantum kernel computation and can achieve high accuracy with only a few qubits.},
keywords = {CSIC-4.7},
pubstate = {published},
tppubtype = {article}
}
Quantum kernel methods leverage a kernel function computed by embedding input information into the Hilbert space of a quantum system. However, large Hilbert spaces can hinder generalization capability, and the scalability of quantum kernels becomes an issue. To overcome these challenges, various strategies under the concept of inductive bias have been proposed. Bandwidth optimization is a promising approach that can be implemented using quantum simulation platforms. We propose trapped-ion simulation platforms as a means to compute quantum kernels, filling a gap in the previous literature and demonstrating their effectiveness for binary classification tasks. We compare the performance of the proposed method with an optimized classical kernel and evaluate the robustness of the quantum kernel against noise. The results show that ion trap platforms are well-suited for quantum kernel computation and can achieve high accuracy with only a few qubits.
Skotiniotis, M.; Llorens, S.; Calsamiglia, J.; Muñoz-Tapia, R.
Topological obstructions to quantum computation with unitary oracles Artículo de revista
En: Physical Review Research, vol. 9, iss. 3, pp. 32625, 2024.
Resumen | Enlaces | BibTeX | Etiquetas: UAB
@article{nokey,
title = {Topological obstructions to quantum computation with unitary oracles},
author = {Skotiniotis, M. and Llorens, S. and Calsamiglia, J. and Muñoz-Tapia, R. },
url = {https://journals.aps.org/pra/abstract/10.1103/PhysRevA.109.032625},
doi = {doi.org/10.1103/PhysRevA.109.032625},
year = {2024},
date = {2024-03-28},
urldate = {2024-03-28},
journal = {Physical Review Research},
volume = {9},
issue = {3},
pages = {32625},
abstract = {Algorithms with unitary oracles can be nested, which makes them extremely versatile. An example is the phase estimation algorithm used in many candidate algorithms for quantum speedup. The search for new quantum algorithms benefits from understanding their limitations: Some tasks are impossible in quantum circuits, although their classical versions are easy, for example, cloning. An example with a unitary oracle 𝑈 is the if clause, the task to implement controlled 𝑈 (up to the phase on 𝑈). In classical computation the conditional statement is easy and essential. In quantum circuits the if clause was shown impossible from one query to 𝑈. Is it possible from polynomially many queries? Here we unify algorithms with a unitary oracle and develop a topological method to prove their limitations: No number of queries to 𝑈 and 𝑈† lets quantum circuits implement the if clause, even if admitting approximations, postselection, and relaxed causality. We also show limitations of process tomography, oracle neutralization, and dim𝑈√𝑈, 𝑈𝑇, and 𝑈† algorithms. Our results strengthen an advantage of linear optics, challenge the experiments on relaxed causality, and motivate new algorithms with many-outcome measurements.},
keywords = {UAB},
pubstate = {published},
tppubtype = {article}
}
Algorithms with unitary oracles can be nested, which makes them extremely versatile. An example is the phase estimation algorithm used in many candidate algorithms for quantum speedup. The search for new quantum algorithms benefits from understanding their limitations: Some tasks are impossible in quantum circuits, although their classical versions are easy, for example, cloning. An example with a unitary oracle 𝑈 is the if clause, the task to implement controlled 𝑈 (up to the phase on 𝑈). In classical computation the conditional statement is easy and essential. In quantum circuits the if clause was shown impossible from one query to 𝑈. Is it possible from polynomially many queries? Here we unify algorithms with a unitary oracle and develop a topological method to prove their limitations: No number of queries to 𝑈 and 𝑈† lets quantum circuits implement the if clause, even if admitting approximations, postselection, and relaxed causality. We also show limitations of process tomography, oracle neutralization, and dim𝑈√𝑈, 𝑈𝑇, and 𝑈† algorithms. Our results strengthen an advantage of linear optics, challenge the experiments on relaxed causality, and motivate new algorithms with many-outcome measurements.
Gonzalez-Conde, J.; Watts, T. W.; Rodriguez-Grasa, P.; Sanz, M.
Efficient quantum amplitude encoding of polynomial functions Artículo de revista
En: Quantum, vol. 8, pp. 1297, 2024, ISBN: 2521-327X.
Resumen | Enlaces | BibTeX | Etiquetas: UPV/EHU
@article{nokey,
title = {Efficient quantum amplitude encoding of polynomial functions},
author = {Gonzalez-Conde, J. and Watts, T.W. and Rodriguez-Grasa, P. and Sanz, M.},
url = {https://quantum-journal.org/papers/q-2024-03-21-1297/},
doi = {doi.org/10.22331/q-2024-03-21-1297},
isbn = {2521-327X},
year = {2024},
date = {2024-03-21},
urldate = {2024-03-21},
journal = {Quantum},
volume = {8},
pages = {1297},
abstract = {Loading functions into quantum computers represents an essential step in several quantum algorithms, such as quantum partial differential equation solvers. Therefore, the inefficiency of this process leads to a major bottleneck for the application of these algorithms. Here, we present and compare two efficient methods for the amplitude encoding of real polynomial functions on n qubits. This case holds special relevance, as any continuous function on a closed interval can be uniformly approximated with arbitrary precision by a polynomial function. The first approach relies on the matrix product state representation. We study and benchmark the approximations of the target state when the bond dimension is assumed to be small. The second algorithm combines two subroutines. Initially we encode the linear function into the quantum registers with a shallow sequence of multi-controlled gates that loads the linear function's Hadamard-Walsh series, exploring how truncating the Hadamard-Walsh series of the linear function affects the final fidelity. Applying the inverse discrete Hadamard-Walsh transform transforms the series coefficients into an amplitude encoding of the linear function. Then, we use this construction as a building block to achieve a block encoding of the amplitudes corresponding to the linear function on k0 qubits and apply the quantum singular value transformation that implements a polynomial transformation to the block encoding of the amplitudes. This unitary together with the Amplitude Amplification algorithm will enable us to prepare the quantum state that encodes the polynomial function on k0 qubits. Finally we pad n−k0 qubits to generate an approximated encoding of the polynomial on n qubits, analyzing the error depending on k0. In this regard, our methodology proposes a method to improve the state-of-the-art complexity by introducing controllable errors.},
keywords = {UPV/EHU},
pubstate = {published},
tppubtype = {article}
}
Loading functions into quantum computers represents an essential step in several quantum algorithms, such as quantum partial differential equation solvers. Therefore, the inefficiency of this process leads to a major bottleneck for the application of these algorithms. Here, we present and compare two efficient methods for the amplitude encoding of real polynomial functions on n qubits. This case holds special relevance, as any continuous function on a closed interval can be uniformly approximated with arbitrary precision by a polynomial function. The first approach relies on the matrix product state representation. We study and benchmark the approximations of the target state when the bond dimension is assumed to be small. The second algorithm combines two subroutines. Initially we encode the linear function into the quantum registers with a shallow sequence of multi-controlled gates that loads the linear function's Hadamard-Walsh series, exploring how truncating the Hadamard-Walsh series of the linear function affects the final fidelity. Applying the inverse discrete Hadamard-Walsh transform transforms the series coefficients into an amplitude encoding of the linear function. Then, we use this construction as a building block to achieve a block encoding of the amplitudes corresponding to the linear function on k0 qubits and apply the quantum singular value transformation that implements a polynomial transformation to the block encoding of the amplitudes. This unitary together with the Amplitude Amplification algorithm will enable us to prepare the quantum state that encodes the polynomial function on k0 qubits. Finally we pad n−k0 qubits to generate an approximated encoding of the polynomial on n qubits, analyzing the error depending on k0. In this regard, our methodology proposes a method to improve the state-of-the-art complexity by introducing controllable errors.
Gasbarri, G.; Bilkis, M.; Roda-Salichs, E.; Calsamiglia, J.
Sequential hypothesis testing for continuously-monitored quantum systems Artículo de revista
En: Quantum, vol. 8, 2024.
Resumen | Enlaces | BibTeX | Etiquetas: UAB
@article{nokey,
title = {Sequential hypothesis testing for continuously-monitored quantum systems},
author = {Gasbarri, G. and Bilkis, M. and Roda-Salichs, E. and Calsamiglia, J. },
url = {https://quantum-journal.org/papers/q-2024-03-20-1289/#},
doi = {doi.org/10.22331/q-2024-03-20-1289},
year = {2024},
date = {2024-03-20},
urldate = {2024-03-20},
journal = {Quantum},
volume = {8},
abstract = {We consider a quantum system that is being continuously monitored, giving rise to a measurement signal. From such a stream of data, information needs to be inferred about the underlying system's dynamics. Here we focus on hypothesis testing problems and put forward the usage of sequential strategies where the signal is analyzed in real time, allowing the experiment to be concluded as soon as the underlying hypothesis can be identified with a certified prescribed success probability. We analyze the performance of sequential tests by studying the stopping-time behavior, showing a considerable advantage over currently-used strategies based on a fixed predetermined measurement time.},
keywords = {UAB},
pubstate = {published},
tppubtype = {article}
}
We consider a quantum system that is being continuously monitored, giving rise to a measurement signal. From such a stream of data, information needs to be inferred about the underlying system's dynamics. Here we focus on hypothesis testing problems and put forward the usage of sequential strategies where the signal is analyzed in real time, allowing the experiment to be concluded as soon as the underlying hypothesis can be identified with a certified prescribed success probability. We analyze the performance of sequential tests by studying the stopping-time behavior, showing a considerable advantage over currently-used strategies based on a fixed predetermined measurement time.
Sannia, A.; Martínez-Peña, R.; Soriano, M.; Giorgi, G. L.; Zambrini, R.
Dissipation as a resource for Quantum Reservoir Computing Artículo de revista
En: Quantum , vol. 8, pp. 1291, 2024.
Resumen | Enlaces | BibTeX | Etiquetas: UIB
@article{nokey,
title = {Dissipation as a resource for Quantum Reservoir Computing},
author = {Sannia, A. and Martínez-Peña, R. and Soriano, M. and Giorgi, G.L. and Zambrini, R. },
url = {https://quantum-journal.org/papers/q-2024-03-20-1291/#},
doi = {doi.org/10.22331/q-2024-03-20-1291},
year = {2024},
date = {2024-03-20},
journal = {Quantum },
volume = {8},
pages = {1291},
abstract = {Dissipation induced by interactions with an external environment typically hinders the performance of quantum computation, but in some cases can be turned out as a useful resource. We show the potential enhancement induced by dissipation in the field of quantum reservoir computing introducing tunable local losses in spin network models. Our approach based on continuous dissipation is able not only to reproduce the dynamics of previous proposals of quantum reservoir computing, based on discontinuous erasing maps but also to enhance their performance. Control of the damping rates is shown to boost popular machine learning temporal tasks as the capability to linearly and non-linearly process the input history and to forecast chaotic series. Finally, we formally prove that, under non-restrictive conditions, our dissipative models form a universal class for reservoir computing. It means that considering our approach, it is possible to approximate any fading memory map with arbitrary precision.},
keywords = {UIB},
pubstate = {published},
tppubtype = {article}
}
Dissipation induced by interactions with an external environment typically hinders the performance of quantum computation, but in some cases can be turned out as a useful resource. We show the potential enhancement induced by dissipation in the field of quantum reservoir computing introducing tunable local losses in spin network models. Our approach based on continuous dissipation is able not only to reproduce the dynamics of previous proposals of quantum reservoir computing, based on discontinuous erasing maps but also to enhance their performance. Control of the damping rates is shown to boost popular machine learning temporal tasks as the capability to linearly and non-linearly process the input history and to forecast chaotic series. Finally, we formally prove that, under non-restrictive conditions, our dissipative models form a universal class for reservoir computing. It means that considering our approach, it is possible to approximate any fading memory map with arbitrary precision.
