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How to build Hamiltonians that transport noncommuting charges in quantum thermodynamics

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arXiv 2021年

作者： Halpern, Nicole Yunger Majidy, Shayan ITAMP Harvard-Smithsonian Center for Astrophysics CambridgeMA02138 United States Department of Physics Harvard University CambridgeMA02138 United States Research Laboratory of Electronics Massachusetts Institute of Technology CambridgeMA02139 United States Center for Theoretical Physics Massachusetts Institute of Technology CambridgeMA02139 United States Joint Center for Quantum Information and Computer Science NIST University of Maryland College ParkMD20742 United States Institute for Physical Science and Technology University of Maryland College ParkMD20742 United States Institute for Quantum Computing University of Waterloo WaterlooONN2L 3G1 Canada Perimeter Institute for Theoretical Physics WaterlooONN2L 2Y5 Canada

Noncommuting conserved quantities have recently launched a subfield of quantum thermodynamics. In conventional thermodynamics, a system of interest and an environment exchange quantities—energy, particles, electric charge, etc.—that are globally conserved and are represented by Hermitian operators. These operators were implicitly assumed to commute with each other, until a few years ago. Freeing the operators to fail to commute has enabled many theoretical discoveries—about reference frames, entropy production, resource-theory models, etc. Little work has bridged these results from abstract theory to experimental reality. This paper provides a methodology for building this bridge systematically: We present a prescription for constructing Hamiltonians that conserve noncommuting quantities globally while transporting the quantities locally. The Hamiltonians can couple arbitrarily many subsystems together and can be integrable or nonintegrable. Our Hamiltonians may be realized physically with superconducting qudits, with ultracold atoms, and with trapped ions. Copyright © 2021, The Authors. All rights reserved.

关键词： Hamiltonians

quantum and classical query complexities for generalized Simon’s problem

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arXiv 2019年

作者： Wu, Zhenggang Qiu, Daowen Tan, Jiawei Li, Hao Cai, Guangya Institute of Quantum Computing and Computer Theory School of Computer Science and Engineering Sun Yat-sen University Guangzhou510006 China The Guangdong Key Laboratory of Information Security Technology Sun Yat-sen University 510006 China

Simon’s problem is an essential example demonstrating the faster speed of quantum computers than classical computers for solving some problems. The optimal separation between exact quantum and classical query complexities for Simon’s problem has been proved by Cai & Qiu. Generalized Simon’s problem can be described as follows. Given a function f : {0, 1}n → {0, 1}m, with the property that there is some unknown hidden subgroup S such that f(x) = f(y) iff x ⊕ y ∈ S, for any x, y ∈ {0, 1}n, where |S| = 2k for some 0 ≤ k ≤ n. The goal is to find S. For the case of k = 1, it is Simon’s problem. In this paper, we propose an exact quantum algorithm with O(n − k) queries and an non-adaptive deterministic classical algorithm with O(k√2n−k) queries for solving the generalized Simon’s problem. Also, we prove that their lower bounds are Ω(n − k) and Ω(√k2n−k), respectively. Therefore, we obtain a tight exact quantum query complexity Θ(n − k) and an almost tight non-adaptive classical deterministic query complexities Ω(√k2n−k) ∼ O(k√2n−k) for this problem. Copyright © 2019, The Authors. All rights reserved.

关键词： quantum theory

Robust charge-density wave correlations in the electron-doped single-band Hubbard model

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arXiv 2022年

作者： Mai, Peizhi Nichols, Nathan S. Karakuzu, Seher Bao, Feng Maestro, Adrian Del Maier, Thomas A. Johnston, Steven Computational Sciences and Engineering Division Oak Ridge National Laboratory Oak RidgeTN37831-6494 United States Department of Physics Institute of Condensed Matter Theory University of Illinois at Urbana-Champaign UrbanaIL61801 United States Data Science and Learning Division Argonne National Laboratory ArgonneIL60439 United States Center for Computational Quantum Physics Flatiron Institute 162 5th Avenue New YorkNY10010 United States Department of Mathematics Florida State University TallahasseeFL32306 United States Department of Physics and Astronomy The University of Tennessee KnoxvilleTN37996 United States Institute of Advanced Materials and Manufacturing The University of Tennessee KnoxvilleTN37996 United States Min H. Kao Department of Electrical Engineering and Computer Science University of Tennessee KnoxvilleTN37996 United States

There is growing evidence that the hole-doped single-band Hubbard and t-J models do not have a superconducting ground state reflective of the high-temperature cuprate superconductors but instead have striped spin- and charge-ordered ground states. Nevertheless, it is proposed that these models may still provide an effective low-energy model for electron-doped materials. Here we study the finite temperature spin and charge correlations in the electron-doped Hubbard model using quantum Monte Carlo dynamical cluster approximation calculations and contrast their behavior with those found on the hole-doped side of the phase diagram. We find evidence for a charge modulation with both checkerboard and unidirectional components decoupled from any spin-density modulations. These correlations are inconsistent with a weak-coupling description based on Fermi surface nesting, and their doping dependence agrees qualitatively with resonant inelastic x-ray scattering measurements. Our results provide evidence that the single-band Hubbard model describes the electron-doped cuprates. © 2022, CC BY.

关键词： Ground state

CircuitQ: An open-source toolbox for superconducting circuits

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arXiv 2021年

作者： Aumann, Philipp Menke, Tim Oliver, William D. Lechner, Wolfgang Institute for Theoretical Physics University of Innsbruck InnsbruckA-6020 Austria Research Laboratory of Electronics Massachusetts Institute of Technology CambridgeMA02139 United States Department of Physics Massachusetts Institute of Technology CambridgeMA02139 United States Department of Physics Harvard University CambridgeMA02138 United States MIT Lincoln Laboratory 244 Wood Street LexingtonMA02420 United States Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology CambridgeMA02139 United States Parity Quantum Computing GmbH InnsbruckA-6020 Austria

We introduce CircuitQ, an open-source toolbox for the analysis of superconducting circuits implemented in Python. It features the automated construction of a symbolic Hamiltonian of the input circuit and a dynamic numerical representation of the Hamiltonian with a variable basis choice. The software implementation is capable of choosing the basis in a fully automated fashion based on the potential energy landscape. Additional features include the estimation of the T1 lifetimes of the circuit states under various noise mechanisms. We review previously established circuit quantization methods and formulate them in a way that facilitates the software implementation. The toolbox is then showcased by applying it to practically relevant qubit circuits and comparing it to specialized circuit solvers. Our circuit quantization is applicable to circuit inputs from a large design space, and the software is open-sourced. We thereby add an important resource for the design of new quantum circuits for quantum information processing applications. © 2021, CC BY.

关键词： Hamiltonians

Mitigating Realistic Noise in Practical Noisy Intermediate-Scale quantum Devices

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Physical Review Applied 2021年第3期15卷 034026-034026页

作者： Jinzhao Sun Xiao Yuan Takahiro Tsunoda Vlatko Vedral Simon C. Benjamin Suguru Endo Clarendon Laboratory University of Oxford Parks Road Oxford OX1 3PU United Kingdom Department of Computer Science Center on Frontiers of Computing Studies Peking University Beijing 100871 China Stanford Institute for Theoretical Physics Stanford University Stanford California 94305 USA Department of Materials University of Oxford Parks Road Oxford OX1 3PH United Kingdom Centre for Quantum Technologies National University of Singapore Singapore 117543 Singapore NTT Secure Platform Laboratories NTT Corporation Musashino 180-8585 Japan

quantum error mitigation (QEM) is vital for noisy intermediate-scale quantum (NISQ) devices. While most conventional QEM schemes assume discrete gate-based circuits with noise appearing either before or after each gate, the assumptions are inappropriate for describing realistic noise that may have strong gate dependence and complicated nonlocal effects, and general computing models such as analog quantum simulators. To address these challenges, we first extend the scenario, where each computation process, being either digital or analog, is described by a continuous time evolution. For noise from imperfections of the engineered Hamiltonian or additional noise operators, we show it can be effectively suppressed by a stochastic QEM method. Since our method assumes only accurate single qubit controls, it is applicable to all digital quantum computers and various analog simulators. Meanwhile, errors in the mitigation procedure can be suppressed by leveraging the Richardson extrapolation method. As we numerically test our method with various Hamiltonians under energy relaxation and dephasing noise and digital quantum circuits with additional two-qubit crosstalk, we show an improvement of simulation accuracy by 2 orders. We assess the resource cost of our scheme and conclude the feasibility of accurate quantum computing with NISQ devices.

关键词： Noise quantum computation quantum error correction quantum gates quantum information processing quantum simulation quantum stochastic processes

Hard jet substructure in a multistage approach

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arXiv 2023年

作者： Tachibana, Y. Kumar, A. Majumder, A. Angerami, A. Arora, R. Bass, S.A. Cao, S. Chen, Y. Dai, T. Du, L. Ehlers, R. Elfner, H. Fan, W. Fries, R.J. Gale, C. He, Y. Heffernan, M. Heinz, U. Jacak, B.V. Jacobs, P.M. Jeon, S. Ji, Y. Kauder, K. Kasper, L. Ke, W. Kelsey, M. Kordell, M. Latessa, J. Lee, Y.-J. Liyanage, D. Lopez, A. Luzum, M. Mak, S. Mankolli, A. Martin, C. Mehryar, H. Mengel, T. Mulligan, J. Nattrass, C. Oliinychenko, D. Paquet, J.-F. Putschke, J.H. Roland, G. Schenke, B. Schwiebert, L. Sengupta, A. Shen, C. Silva, A. Sirimanna, C. Soeder, D. Soltz, R.A. Soudi, I. Staudenmaier, J. Strickland, M. Velkovska, J. Vujanovic, G. Wang, X.-N. Wolpert, R.L. Zhao, W. Akita International University Yuwa Akita010-1292 Japan Department of Physics McGill University MontréalQCH3A2T8 Canada Department of Physics and Astronomy Wayne State University DetroitMI48201 United States Department of Physics University of Regina ReginaSKS4S 0A2 Canada Lawrence Livermore National Laboratory LivermoreCA94550 United States Research Computing Group University Technology Solutions The University of Texas at San Antonio San AntonioTX78249 United States Department of Physics Duke University DurhamNC27708 United States Institute of Frontier and Interdisciplinary Science Shandong University Shandong Qingdao266237 China Laboratory for Nuclear Science Massachusetts Institute of Technology CambridgeMA02139 United States Department of Physics Massachusetts Institute of Technology CambridgeMA02139 United States Department of Physics and Astronomy Vanderbilt University NashvilleTN37235 United States Department of Physics and Astronomy University of Tennessee KnoxvilleTN37996 United States Physics Division Oak Ridge National Laboratory Oak RidgeTN37830 United States Department of Physics University of California BerkeleyCA94270 United States Nuclear Science Division Lawrence Berkeley National Laboratory BerkeleyCA94270 United States GSI Helmholtzzentrum für Schwerionenforschung Darmstadt64291 Germany Institute for Theoretical Physics Goethe University Frankfurt am Main60438 Germany Frankfurt Institute for Advanced Studies Frankfurt am Main60438 Germany Cyclotron Institute Texas A&M University College StationTX77843 United States Department of Physics and Astronomy Texas A&M University College StationTX77843 United States Guangdong Provincial Key Laboratory of Nuclear Science Institute of Quantum Matter South China Normal University Guangzhou510006 China Guangdong-Hong Kong Joint Laboratory of Quantum Matter Southern Nuclear Science Computing Center South China Normal University Guangzhou510006 China Depar

We present predictions and postdictions for a wide variety of hard jet-substructure observables using a multistage model within the jetscape framework. The details of the multistage model and the various parameter choices are described in [Phys. Rev. C 107, 034911 (2023)]. A novel feature of this model is the presence of two stages of jet modification: a high virtuality phase [modeled using the matter modular all twist transverse-scattering elastic-drag and radiation model (matter)], where modified coherence effects diminish medium-induced radiation, and a lower virtuality phase [modeled using the linear Boltzmann transport model (lbt)], where parton splits are fully resolved by the medium as they endure multiple scattering induced energy loss. Energy-loss calculations are carried out on event-by-event viscous fluid dynamic backgrounds constrained by experimental data. The uniform and consistent descriptions of multiple experimental observables demonstrate the essential role of modified coherence effects and the multistage modeling of jet evolution. Using the best choice of parameters from [Phys. Rev. C 107, 034911 (2023)], and with no further tuning, we present calculations for the medium modified jet fragmentation function, the groomed jet momentum fraction zg and angular separation rg distributions, as well as the nuclear modification factor of groomed jets. These calculations provide accurate descriptions of published data from experiments at the Large Hadron Collider. Furthermore, we provide predictions from the multistage model for future measurements at the BNL Relativistic Heavy Ion Collider. Copyright © 2023, The Authors. All rights reserved.

关键词： Multiple scattering

XYZ spectroscopy at electron-hadron facilities. II. Semi-inclusive processes with pion exchange

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Physical Review D 2022年第9期106卷 094009-094009页

作者： D. Winney A. Pilloni V. Mathieu A. N. Hiller Blin M. Albaladejo W. A. Smith A. Szczepaniak Guangdong Provincial Key Laboratory of Nuclear Science Institute of Quantum Matter South China Normal University Guangzhou 510006 China Guangdong-Hong Kong Joint Laboratory of Quantum Matter Southern Nuclear Science Computing Center South China Normal University Guangzhou 510006 China Dipartimento di Scienze Matematiche e Informatiche Scienze Fisiche e Scienze della Terra Università degli Studi di Messina I-98122 Messina Italy INFN Sezione di Catania I-95123 Catania Italy Departament de Física Quàntica i Astrofísica and Institut de Ciències del Cosmos Universitat de Barcelona E-08028 Spain Institute for Theoretical Physics Regensburg University D-93040 Regensburg Germany Institute for Theoretical Physics Tübingen University Auf der Morgenstelle 14 72076 Tübingen Germany Instituto de Física Corpuscular (IFIC) Centro Mixto CSIC-Universidad de Valencia E-46071 Valencia Spain Center for Exploration of Energy and Matter Indiana University Bloomington Indiana 47403 USA Department of Physics Indiana University Bloomington Indiana 47405 USA Theory Center Thomas Jefferson National Accelerator Facility Newport News Virginia 23606 USA

Semi-inclusive processes are very promising to investigate XYZ hadrons at the next generation of electron-hadron facilities, because they generally boast higher cross sections. We extend our formalism of exclusive photoproduction to semi-inclusive final states. The inclusive production cross sections for charged axial-vector Z states from pion exchange are predicted. We isolate the contribution of Δ resonances at small missing mass. Production near threshold is shown to be enhanced roughly by a factor of two compared to the exclusive reaction. We benchmark the model with data of semi-inclusive b1± production.

关键词： Exotic mesons Quarkonia Lepton-hadron colliders

Wigner negativity in spin-j systems

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Physical Review Research 2021年第3期3卷 033134-033134页

作者： Jack Davis Meenu Kumari Robert B. Mann Shohini Ghose Department of Physics and Astronomy University of Waterloo Waterloo Ontario N2L 3G1 Canada Institute for Quantum Computing University of Waterloo Waterloo Ontario N2L 3G1 Canada Perimeter Institute for Theoretical Physics 31 Caroline Street North Waterloo Ontario N2L 2Y5 Canada Department of Physics and Computer Science Wilfrid Laurier University Waterloo Ontario N2L 3C5 Canada

The nonclassicality of simple spin systems as measured by Wigner negativity is studied on a spherical phase space. Several SU(2)-covariant states with common qubit representations are analyzed: spin coherent states, spin cat (Greenberger-Horne-Zeilinger or N00N) states, and Dicke (W) states. We derive a bound on the Wigner negativity of spin cat states that rapidly approaches the true value as spin increases beyond j≳5. We find that spin cat states are not significantly Wigner negative relative to their Dicke state counterparts of equal dimension. We also find, in contrast to several entanglement measures, that the most Wigner-negative Dicke basis element is spin dependent, and not the equatorial state |j,0〉 (or |j,±1/2〉 for half-integer spins). These results underscore the influence that dynamical symmetry has on nonclassicality and suggest a guiding perspective for finding novel quantum computational applications.

关键词： quantum correlations in quantum information quantum information with atoms & light quantum optics Atomic ensemble Phase space methods

A benchmark test of boson sampling on Tianhe-2 supercomputer

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National science Review 2018年第5期5卷 715-720页

作者： Junjie Wu Yong Liu Baida Zhang Xianmin Jin Yang Wang Huiquan Wang Xuejun Yang Institute for Quantum Information & State Key Laboratory of High Performance Computing College of ComputerNational University of Defense Technology State Key Laboratory of Advanced Optical Communication Systems and Networks School of Physics and AstronomyShanghai Jiao Tong University Synergetic Innovation Center of Quantum Information and Quantum Physics University of Science and Technology of China

Boson sampling, thought to be intractable classically, can be solved by a quantum machine composed of merely generation, linear evolution and detection of single photons. Such an analog quantum computer for this specific problem provides a shortcut to boost the absolute computing power of quantum computers to beat classical ones. However, the capacity bound of classical computers for simulating boson sampling has not yet been identified. Here we simulate boson sampling on the Tianhe-2 supercomputer, which occupied the first place in the world ranking six times from 2013 to 2016. We computed the permanent of the largest matrix using up to 312 000 CPU cores of Tianhe-2, and inferred from the current most efficient permanent-computing algorithms that an upper bound on the performance of Tianhe-2 is one 50-photon sample per ～100 min. In addition, we found a precision issue with one of two permanent-computing algorithms.

关键词： boson sampling permanent quantum supremacy quantum computing supercomputer