Article
Physics, Multidisciplinary
Bertrand Evrard, An Qu, Jean Dalibard, Fabrice Gerbier
Summary: The dynamics of a many-body system can exhibit various behaviors, from reversible evolution to thermalization. The linear energy spectrum and undamped oscillations of many-body observables occur when the system can be described by a Bogoliubov analysis, while nonlinearity leads to irreversibility. Chaotic dynamics and thermalization emerge when the integrability of the Hamiltonian is broken, in agreement with the eigenstate thermalization hypothesis paradigm.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
Riccarda Bonsignori, Pasquale Calabrese
Summary: The study focuses on the symmetry resolved entanglement entropies in one-dimensional systems with boundaries, providing general results for conformal invariant theories. Exact formulas for charged and symmetry resolved entropies are derived based on spectra of Toeplitz+Hankel matrices. The saddle-point approximation introduces algebraic corrections to the scaling particularly severe in systems with boundaries.
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2021)
Article
Physics, Multidisciplinary
Yunyan Yao, Liang Xiang, Zexian Guo, Zehang Bao, Yong-Feng Yang, Zixuan Song, Haohai Shi, Xuhao Zhu, Feitong Jin, Jiachen Chen, Shibo Xu, Zitian Zhu, Fanhao Shen, Ning Wang, Chuanyu Zhang, Yaozu Wu, Yiren Zou, Pengfei Zhang, Hekang Li, Zhen Wang, Chao Song, Chen Cheng, Rubem Mondaini, H. Wang, J. Q. You, Shi-Yao Zhu, Lei Ying, Qiujiang Guo
Summary: A superconducting qubit experiment demonstrates the benefits of studying many-body problems in Fock space, providing insights into quantum dynamics and criticality. Quantum simulation offers a controlled way to explore fundamental aspects of many-body physics and their implications for quantum technology. However, investigating strongly correlated problems in real space using few-body probes is often insufficient due to the exponential growth of the Hilbert space with the number of interacting particles.
Article
Physics, Multidisciplinary
Johannes Feldmeier, Michael Knap
Summary: The research suggests that in certain constrained many-body systems, the structure of conservation laws may cause a drastic modification of the universal behavior of the far-from-equilibrium dynamics of quantum systems characterized by the ballistic spreading of initially local operators. By studying operator growth in a dipole-conserving fracton chain, a critical point with subballistic moving properties separating a ballistic phase from a dynamically frozen phase is identified, which is tied to an underlying localization transition.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
Jonah Kudler-Flam, Ramanjit Sohal, Laimei Nie
Summary: This paper investigates the role of conservation laws in the thermalization process from an information-theoretic perspective in non-integrable systems. It shows that even when a system conserves energy, the maximal amount of information is still scrambled at late times, but the amount of scrambled information decreases when the system has additional symmetries leading to degeneracies in the spectrum.
Article
Physics, Multidisciplinary
S. J. Garratt, J. T. Chalker
Summary: The study presents a framework where the transition between a many-body localized phase and an ergodic phase is achieved through symmetry breaking. It explores random Floquet spin chains and how their averaged spectral form factor is influenced by the leading eigenvalues of a transfer matrix. The research identifies broken symmetry within the transfer matrix and introduces a local order parameter for the transition, showing that long-ranged correlation functions are only present in the ergodic phase.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
Qiujiang Guo, Chen Cheng, Zheng-Hang Sun, Zixuan Song, Hekang Li, Zhen Wang, Wenhui Ren, Hang Dong, Dongning Zheng, Yu-Ran Zhang, Rubem Mondaini, Heng Fan, H. Wang
Summary: The study of many-body localization phenomenon revealed the crucial role played by initial energy using a quantum processor with programmable superconducting processor. The onset of localization was found to occur at different disorder strengths with distinguishable energy scales, as observed through time-evolved observables and quantities related to many-body wave functions. This opens avenues for experimental exploration of many-body mobility edges in MBL systems.
Article
Physics, Fluids & Plasmas
Felix Fritzsch, Tomaz Prosen
Summary: In this paper, we introduce a perturbed free quantum circuit model that exhibits ergodicity induced by an impurity interaction placed on the system's boundary. By combining numerical calculations and analytical arguments, we find that in a certain scaling limit, correlations in the system exponentially decay with system size for impurities that remain unitary under partial transpose, while generic impurities or generic locations of local operators result in persistent revivals of correlations with a period given by the system size.
Article
Physics, Multidisciplinary
C. J. Turner, J-Y Desaules, K. Bull, Z. Papic
Summary: The text explains key concepts and findings in the theory of quantum scarring, demonstrating that quasimodes arise from previously established periodic orbits when quantum fluctuations are restored. The results shed light on the role of the TDVP classical system in Rydberg atom chains and its impact on the system.
Article
Physics, Multidisciplinary
Chen-Te Ma, Chih-Hung Wu
Summary: The study explores the relationship between Quantum Entanglement and Quantum Chaos, using methods such as the Gaussian random model to conduct universal research, analyzing the positive correlation between the violation of Bell's inequality and entanglement entropy, and examining the relations between entanglement quantities and dip time, dynamics, and chaotic signaling criteria.
INTERNATIONAL JOURNAL OF THEORETICAL PHYSICS
(2022)
Article
Physics, Multidisciplinary
Jie Ren, Chenguang Liang, Chen Fang
Summary: In quantum systems, a subspace spanned by degenerate eigenvectors of the Hamiltonian may have higher symmetries than those of the Hamiltonian itself. Coupling an external field to certain generators of the quasisymmetry group can lift the degeneracy and result in exactly periodic dynamics within the degenerate subspace.
PHYSICAL REVIEW LETTERS
(2021)
Article
Physics, Multidisciplinary
Lata Kh Joshi, Andreas Elben, Amit Vikram, Benoit Vermersch, Victor Galitski, Peter Zoller
Summary: The statistics of energy eigenvalues are important for understanding many-body quantum chaos, and partial spectral form factors can provide insights into subsystems of many-body systems. We propose a protocol that uses randomized measurements to measure the spectral form factor and partial spectral form factors in quantum many-body spin models.
Article
Quantum Science & Technology
Erik J. Gustafson, Andy C. Y. Li, Abid Khan, Joonho Kim, Doga Murat Kurkcuoglu, M. Sohaib Alam, Peter P. Orth, Armin Rahmani, Thomas Iadecola
Summary: Quantum many-body scar states, which exhibit atypical entanglement and correlation properties, can be studied using state preparation protocols on quantum computers. Experimental demonstrations on superconducting quantum hardware have been provided.
Article
Mechanics
Federico Rottoli, Sara Murciano, Erik Tonni, Pasquale Calabrese
Summary: We investigate the ground-state entanglement Hamiltonian of massless Dirac fermions on the half-line for multiple disjoint intervals. It comprises a local part and a bi-local term that couples each point to another one in each interval. The bi-local operator can be either diagonal or mixed in fermionic chiralities and it is sensitive to the boundary conditions. Understanding this entanglement Hamiltonian is crucial in evaluating the negativity Hamiltonian, which characterizes the entanglement of subsystems in mixed states. We find that the negativity Hamiltonian inherits the structure of the corresponding entanglement Hamiltonian. Finally, we demonstrate how the continuum expressions for both operators can be obtained from exact numerical computations in free-fermion chains.
JOURNAL OF STATISTICAL MECHANICS-THEORY AND EXPERIMENT
(2023)
Article
Physics, Multidisciplinary
Song He
Summary: In this study, we investigated generic n-point correlation functions of conformal field theories (CFTs) with TT and JT deformations using the perturbative CFT approach. We systematically derived the first order correction to the generic correlation functions of CFTs with TT or JT deformation. The computation of the out of time ordered correlation function (OTOC) in the Ising model with TT or JT deformation confirmed that these deformations do not alter the integrable property up to the first order level.
SCIENCE CHINA-PHYSICS MECHANICS & ASTRONOMY
(2021)
Article
Physics, Multidisciplinary
Matthias Gruber, Viktor Eisler
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2020)
Article
Chemistry, Physical
Lexin Ding, Sam Mardazad, Sreetama Das, Szilard Szalay, Ulrich Schollwoeck, Zoltan Zimboras, Christian Schilling
Summary: The recent development in quantum chemistry highlights the quantum mutual information between orbitals as a major descriptor of electronic structure, leading to significant improvements in numerical methods. By introducing physical correlation and separating it into classical and quantum parts, our work quantifies entanglement and raises questions about its general significance in chemical bonding. The implementation of the fundamental particle number superselection rule removes a major part of correlation and entanglement, suggesting that quantum information processing tasks with molecular systems may be more challenging than expected.
JOURNAL OF CHEMICAL THEORY AND COMPUTATION
(2021)
Article
Physics, Multidisciplinary
Matthias Gruber, Viktor Eisler
Summary: In this study, we investigate the spreading of entanglement produced by the time evolution of a local fermionic excitation above the ground state of the XXZ chain. The resulting entropy profiles are analyzed through density-matrix renormalization group calculations and compared to a quasiparticle ansatz. The dominant carriers of entanglement are assumed to be spinon excitations traveling at different velocities, with the entropy profile being reproduced by a probabilistic expression involving the density fraction of these spinons reaching the subsystem.
Article
Physics, Multidisciplinary
Viktor Eisler
Summary: This study examines the time evolution of entanglement created by local or extended excitations on the ground state of a free-fermion chain. A single particle or hole excitation leads to excess entropy increasing linearly with time and subsystem lengths. In the case of double hole excitations, some coherence is preserved between the excitations only for large separations, while coherence is lost for particle-hole excitations. Multiple hole excitations on a completely filled chain show that excess entropy scales logarithmically for an extended contiguous hole and linearly for finite separations between the holes.
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2021)
Review
Physics, Multidisciplinary
Szilard Szalay, Zoltan Zimboras, Mihaly Mate, Gergely Barcza, Christian Schilling, Ors Legeza
Summary: The operator algebra of fermionic modes is isomorphic to that of qubits, with fundamental differences in the embedding of subalgebras and the parity superselection. New tools for fermionic systems, such as the fermionic tensor product and fermionic canonical embedding, are developed from a quantum information theory perspective. Additionally, variants of fermionic mode correlation and entanglement are considered, along with the inevitability of parity superselection in describing fermionic systems.
JOURNAL OF PHYSICS A-MATHEMATICAL AND THEORETICAL
(2021)
Article
Quantum Science & Technology
Filip B. Maciejewski, Flavio Baccari, Zoltan Zimboras, Michal Oszmaniec
Summary: Measurement noise in quantum devices based on superconducting qubits is a significant source of errors, and the complexity of its characterization and mitigation can be challenging. The introduction of a correlated measurement noise model in this work allows for efficient noise-mitigation at the marginal probability distribution level. Experimental results on IBM and Rigetti devices demonstrate a significant reduction in errors with this noise-mitigation scheme. Additionally, the study shows that correlations in measurement noise do not necessarily match the physical layout of the device, and noise-mitigation can improve the performance of the Quantum Approximate Optimization Algorithm (QAOA).
Article
Chemistry, Multidisciplinary
Szabolcs Joczik, Zoltan Zimboras, Tamas Majoros, Attila Kiss
Summary: Numerical simulations are widely used in various industries, including product development. The finite element method is one of the most commonly used numerical methods for solving differential equations that describe the physics behind the simulations. However, there are still challenges in numerically simulating complex real-life processes. This paper proposes a cost-efficient method for applying quantum algorithms in finite element analysis, which addresses the limitations and cost efficiency of available quantum hardware.
APPLIED SCIENCES-BASEL
(2022)
Article
Quantum Science & Technology
Adam Glos, Aleksandra Krawiec, Zoltan Zimboras
Summary: In the era of NISQ computers, it is important to design quantum algorithms that do not require many qubits or deep circuits. This paper demonstrates how to reduce the number of qubits needed for the Traveling Salesman Problem and proposes encoding schemes that can be efficiently implemented within the Quantum Approximate Optimization Algorithm framework.
NPJ QUANTUM INFORMATION
(2022)
Article
Mechanics
Viktor Eisler, Erik Tonni, Ingo Peschel
Summary: This paper investigates the ground state of free-fermion chains and the entanglement Hamiltonian for a subsystem consisting of two separated intervals. In this case, there is a peculiar long-range hopping between the intervals in addition to the well-known short-range hopping. The authors show how to obtain continuum expressions from lattice results for general filling and arbitrary intervals. They also discuss the closely related case of a single interval located at a certain distance from the end of a semi-infinite chain and the continuum limit for this problem. Finally, they demonstrate the existence of a commuting operator in the continuum for the double interval, which can be used to find the eigenstates.
JOURNAL OF STATISTICAL MECHANICS-THEORY AND EXPERIMENT
(2022)
Review
Physics, Multidisciplinary
Marcello Dalmonte, Viktor Eisler, Marco Falconi, Benoit Vermersch
Summary: This review summarizes the results about entanglement (or modular) Hamiltonians of quantum many-body systems in field theory and statistical mechanics models, and recent applications in the context of quantum information and quantum simulation. The first part of the review discusses the known results about entanglement Hamiltonians of ground states in quantum field theory, based on the Bisognano-Wichmann theorem and its extension to conformal field theory. The second part focuses on lattice models, considering both soluble and non-integrable cases. The review also covers recently developed applications in quantum information processing that rely on the specific properties of entanglement Hamiltonians.
ANNALEN DER PHYSIK
(2022)
Article
Quantum Science & Technology
Michal Oszmaniec, Ninnat Dangniam, Mauro E. S. Morales, Zoltan Zimboras
Summary: Fermionic linear optics (FLO) is a model of quantum computation that can demonstrate quantum computational advantages with suitable input states. By using fermion sampling and different classes of circuits, it is possible to prove the hardness guarantees of computing output probabilities. FLO circuits are relevant for quantum chemistry and many-body physics, and can be experimentally verified.
Proceedings Paper
Quantum Science & Technology
Daniel Nagy, Zsolt Tabi, Peter Haga, Zsofia Kallus, Zoltan Zimboras
Summary: In recent years, noisy intermediate scale quantum (NISQ) computing devices have become available, with quantum machine learning emerging as a promising application area. This study utilizes continuous-variable quantum machine learning to solve classical continuous control problems, presenting performance assessment using proximal policy optimization for photonic variational quantum agents and data re-uploading. The results show that the photonic policy learning achieves comparable performance levels and faster convergence than classical neural networks for the restricted CartPole problem.
2021 IEEE INTERNATIONAL CONFERENCE ON QUANTUM COMPUTING AND ENGINEERING (QCE 2021) / QUANTUM WEEK 2021
(2021)
Article
Computer Science, Information Systems
Zsolt Tabi, Adam Marosits, Zsofia Kallus, Peter Vaderna, Istvan Godor, Zoltan Zimboras
Summary: This study compares Maximum Likelihood Channel Decoder problems for MIMO scenarios in Centralized Radio Access Network architectures using Quantum Annealing. The experiments analyze more complex modulations and larger MIMO antenna array sizes, revealing the limits of state-of-the-art quantum optimization for massive MIMO ML decoders. The study includes an enhanced evaluation of raw annealer sampling through post-processing methods in a comparative analysis between D-Wave 2000Q and the D-Wave Advantage system.
Article
Materials Science, Multidisciplinary
David Jakab, Zoltan Zimboras
Summary: We study a bipartite collective spin-1 model with exchange interaction, where spins are divided into two equal-sized subsystems with equal interactions within and across each subsystem but different coupling values. Using symmetry and representation theoretic methods, the Hamiltonian of the system is diagonalized and the ground-state phase diagram is explored, revealing both gapped and gapless phases. Interestingly, one phase shows strong bipartite symmetry breaking with the two subsystems in different SU(3) representations.
Article
Telecommunications
Adam Marosits, Zsolt Tabi, Zsofia Kallus, Peter Vaderna, Istvan Godor, Zoltan Zimboras
Summary: Quantum Annealing is a heuristic method using quantum mechanics to solve Quadratic Unconstrained Binary Optimization problems, with existing processing units available via cloud platform access. This paper explores the applicability of ML Channel Decoder in MIMO scenarios for centralized RAN, facing challenges of exponential solution space increase with demand for higher data rates. Leveraging Quantum Annealing for large MIMO problems with more complex modulation and higher transmitter/receiver numbers is explored using the D-Wave Advantage system.
INFOCOMMUNICATIONS JOURNAL
(2021)
