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We extend quantum kinetic theory to deal with a strongly Bose-condensed atomic vapor in a trap. The method assumes that the majority of the vapor is not condensed, and acts as a bath of heat and atoms for the condensate. The condensate is…

Statistical Mechanics · Physics 2009-10-30 C. W. Gardiner , P. Zoller

We present a deep neural network (DNN)-based model (HubbardNet) to variationally find the ground state and excited state wavefunctions of the one-dimensional and two-dimensional Bose-Hubbard model. Using this model for a square lattice with…

Strongly Correlated Electrons · Physics 2023-09-04 Ziyan Zhu , Marios Mattheakis , Weiwei Pan , Efthimios Kaxiras

The structure of the thermal equilibrium state of a weakly interacting Bose gas is of current interest. We calculate the density matrix of that state in two ways. The most effective method, in terms of yielding a simple, explicit answer, is…

General Relativity and Quantum Cosmology · Physics 2022-10-12 S. A. Fulling , B. -G. Englert , M. D. Pilloff

We present a procedure to construct tensor-network representations of many-body Gaussian states efficiently and with a controllable error. These states include the ground and thermal states of bosonic and fermionic quadratic Hamiltonians,…

Quantum Physics · Physics 2021-07-21 Alexander Nüßeler , Ish Dhand , Susana F. Huelga , Martin B. Plenio

This study investigates the thermal properties of the repulsive Fermi-Hubbard model with chemical potential using variational quantum algorithms, crucial in comprehending particle behaviour within lattices at high temperatures in condensed…

Quantum Physics · Physics 2024-06-17 Jack Y. Araz , Michael Spannowsky , Matthew Wingate

We present the first experimental measurement of the ensemble averages of both the kinetic and interaction energies of the three-dimensional Bose--Hubbard model at finite temperature and various optical lattice depths across weakly to…

We suggest a generalisation of the expression of the nonequilibrium density matrix obtained by Hershfield's method for the cases where both heat and charge steady state currents are present in a quantum open system. The finite-size quantum…

Mesoscale and Nanoscale Physics · Physics 2014-12-15 H. Ness

We study a distribution of thermal states given by random Hamiltonians with a local structure. We show that the ensemble of thermal states monotonically approaches the unitarily invariant ensemble with decreasing temperature if all…

Quantum Physics · Physics 2014-12-03 Yoshifumi Nakata , Tobias J. Osborne

We develop a constructive approach to generate artificial neural networks representing the exact ground states of a large class of many-body lattice Hamiltonians. It is based on the deep Boltzmann machine architecture, in which two layers…

Disordered Systems and Neural Networks · Physics 2018-12-18 Giuseppe Carleo , Yusuke Nomura , Masatoshi Imada

Preparing thermal equilibrium states is an essential task for finite-temperature quantum simulations. In statistical mechanics, microstates in thermal equilibrium can be obtained from statistical ensembles. To date, numerous ensembles have…

Quantum Physics · Physics 2025-05-23 Yasushi Yoneta

Many-body physics is one very well suited field for testing quantum algorithms and for finding working heuristics on present quantum computers. We have investigated the non-equilibrium dynamics of one- and two-electron systems, which are…

Quantum Physics · Physics 2022-07-06 Sabine Tornow , Wolfgang Gehrke , Udo Helmbrecht

Many-body localized (MBL) phases of disordered quantum many-particle systems have a number of unique properties, including failure to act as a thermal bath and protection of quantum coherence. Studying MBL is complicated by the effects of…

Disordered Systems and Neural Networks · Physics 2022-01-03 Michael Sonner , Alessio Lerose , Dmitry A. Abanin

We present a method of using a nuclear magnetic resonance computer to solve the Deutsch-Jozsa problem in which: (1) the number of molecules in the NMR sample is irrelevant to the number of qubits available to an NMR quantum computer, and…

Quantum Physics · Physics 2009-11-13 Amr F. Fahmy , Raimund Marx , Wolfgang Bermel , Steffen J. Glaser

The recently developed density matrix quantum Monte Carlo (DMQMC) algorithm stochastically samples the N -body thermal density matrix and hence provides access to exact properties of many-particle quantum systems at arbitrary temperatures.…

Strongly Correlated Electrons · Physics 2015-10-15 Fionn D. Malone , N. S. Blunt , James J. Shepherd , D. K. K. Lee , J. S. Spencer , W. M. C. Foulkes

We present an ab-initio approach for grand canonical ensembles in thermal equilibrium with local or nonlocal external potentials based on the one-reduced density matrix. We show that equilibrium properties of a grand canonical ensemble are…

Other Condensed Matter · Physics 2015-08-03 Tim Baldsiefen , Attila Cangi , E. K. U. Gross

We study in this article how heat can be exchanged between two level systems (TLS) each of them being coupled to a thermal reservoir. Calculation are performed solving a master equation for the density matrix using the Born…

Quantum Physics · Physics 2017-03-08 Karl Joulain , Younes Ezzahri , Jose Ordonez-Miranda

The representation of a quantum wave function as a neural network quantum state (NQS) provides a powerful variational ansatz for finding the ground states of many-body quantum systems. Nevertheless, due to the complex variational landscape,…

Quantum Physics · Physics 2023-12-06 Eimantas Ledinauskas , Egidijus Anisimovas

We present a methodology to simulate the quantum thermodynamics of thermal machines which are built from an interacting working medium in contact with fermionic reservoirs at fixed temperature and chemical potential. Our method works at…

Strongly Correlated Electrons · Physics 2020-08-21 Marlon Brenes , Juan José Mendoza-Arenas , Archak Purkayastha , Mark T. Mitchison , Stephen R. Clark , John Goold

An interacting quantum system that is subject to disorder may cease to thermalize due to localization of its constituents, thereby marking the breakdown of thermodynamics. The key to our understanding of this phenomenon lies in the system's…

Variational methods have offered controllable and powerful tools for capturing many-body quantum physics for decades. The recent introduction of expressive neural network quantum states has enabled the accurate representation of a broad…

Quantum Physics · Physics 2025-10-20 Matija Medvidović , Alev Orfi , Juan Carrasquilla , Dries Sels
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