232 citations · 1.3k across the 64 of their papers we have counts for
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Second law of thermodynamics in closed quantum many-body systems
Yuuya Chiba, Yasushi Yoneta, Ryusuke Hamazaki +1
The second law of thermodynamics for adiabatic operations -- constraints on state transitions in closed systems under external control -- is one of the fundamental principles of th…
Key Observable for Linear Thermalization
Yuuya Chiba, Akira Shimizu
For studies on thermalization of an isolated quantum many-body system, the fundamental issue is to determine whether a given system thermalizes or not. However, most studies tested…
Statistical ensembles for phase coexistence states specified by noncommutative additive observables
Yasushi Yoneta, Akira Shimizu
A phase coexistence state cannot be specified uniquely by any intensive parameters, such as the temperature and the magnetic field, because they take the same values over all coexi…
Anomalous Behavior of Magnetic Susceptibility Obtained by Quench Experiments in Isolated Quantum Systems
Yuuya Chiba, Kenichi Asano, Akira Shimizu
We examine how the magnetic susceptibility obtained by the quench experiment on isolated quantum systems is related to the isothermal and adiabatic susceptibilities defined in ther…
Squeezed ensemble for systems with first-order phase transitions
Yasushi Yoneta, Akira Shimizu
All ensembles of statistical mechanics are equivalent in the sense that they give the equivalent thermodynamic functions in the thermodynamic limit. However, when investigating mic…
From Linear to Nonlinear Responses of Thermal Pure Quantum States
Hiroyuki Endo, Chisa Hotta, Akira Shimizu
We propose a self-validating scheme to calculate the unbiased responses of quantum many-body systems to external fields of arbibraty strength at any temperature. By switching on a…
Macroscopic Quantum Violation of Fluctuation-Dissipation Theorem in Equilibrium
Kentaro Kubo, Kenichi Asano, Akira Shimizu
We examine the Hall conductivity of macroscopic two-dimensional quantum system, and show that the observed quantities can sometimes violate the fluctuation dissipation theorem (FDT…
Quantum Violation of Fluctuation-Dissipation Theorem
Akira Shimizu, Kyota Fujikura
We study quantum measurements of temporal equilibrium fluctuations in macroscopic quantum systems. It is shown that the fluctuation-dissipation theorem, as a relation between obser…
Universal Property of Quantum Measurements of Equilibrium Fluctuations and Violation of Fluctuation-Dissipation Theorem
Kyota Fujikura, Akira Shimizu
For macroscopic quantum systems, we study what are measured when equilibrium fluctuations of macrovariables are measured in an ideal way that mimics classical ideal measurements as…
Liquid is More Rigid than Solid in a High-Frequency Region
Naoki Hasegawa, Tatsuro Yuge, Akira Shimizu
We compare rigidity of materials in two phases, liquid and solid phases. As a measure of the rigidity, we employ the one characterizing how firmly the material is fixed by low dens…
Thermal Pure Quantum States of Many-Particle Systems
Masahiko Hyuga, Sho Sugiura, Kazumitsu Sakai +1
We generalize the thermal pure quantum (TPQ) formulation of statistical mechanics, in such a way that it is applicable to systems whose Hilbert space is infinite dimensional. Assum…
New Formulation of Statistical Mechanics using Thermal Pure Quantum States
Sho Sugiura, Akira Shimizu
We formulate statistical mechanics based on a pure quantum state, which we call a ``thermal pure quantum (TPQ) state''. A single TPQ state gives not only equilibrium values of mech…
Canonical Thermal Pure Quantum State
Sho Sugiura, Akira Shimizu
A thermal equilibrium state of a quantum many-body system can be represented by a typical pure state, which we call a thermal pure quantum (TPQ) state. We construct the canonical T…
Thermal Pure Quantum States at Finite Temperature
Sho Sugiura, Akira Shimizu
An equilibrium state can be represented by a pure quantum state, which we call a thermal pure quantum (TPQ) state. We propose a new TPQ state and a simple method of obtaining it. A…
Nonequilibrium Molecular Dynamics Simulation of Interacting Many Electrons Scattered by Lattice Vibrations
Fan Lee, Tatsuro Yuge, Akira Shimizu
We propose a new model suitable for a nonequilibrium molecular dynamics (MD) simulation of electrical conductors. The model consists of classical electrons and atoms. The atoms com…
Universal Properties of Nonlinear Response Functions of Nonequilibrium Steady States
Akira Shimizu
We derive universal properties of nonlinear response functions of nonequilibrium steady states. In particular, sum rules and asymptotic behaviors are derived. Their consequences ar…
General properties of response functions of nonequilibrium steady states
Akira Shimizu, Tatsuro Yuge
We derive general properties, which hold for both quantum and classical systems, of response functions of nonequilibrium steady states. We clarify differences from those of equilib…
Indications of Universal Excess Fluctuations in Nonequilibrium Systems
Tatsuro Yuge, Akira Shimizu
The fluctuation in electric current in nonequilibrium steady states is investigated by molecular dynamics simulation of macroscopically uniform conductors. At low frequencies, appr…
Long-time tail in an electric conduction system
Tatsuro Yuge, Akira Shimizu
The long-time behavior of the velocity autocorrelation function in a classical two-dimensional electric conduction system is studied by the molecular dynamics simulation. In equili…
Long-Time Behavior of Velocity Autocorrelation Function for Interacting Particles in a Two-Dimensional Disordered System
Tatsuro Yuge, Akira Shimizu
The long-time behavior of the velocity autocorrelation function (VACF) is investigated by the molecular dynamics simulation of a two-dimensional system which has both a many-body i…
Energies and collapse times of symmetric and symmetry-breaking states of finite systems with a U(1) symmetry
Akira Shimizu, Takayuki Miyadera
We study quantum systems of volume V, which will exhibit the breaking of a U(1) symmetry in the limit of V \to \infty, when V is large but finite. We estimate the energy difference…
Charge superselection rule does not rule out pure states of subsystems to be coherent superpositions of states with different charges
Akira Shimizu, Takayuki Miyadera
We consider a huge quantum system that is subject to the charge superselection rule, which requires that any pure state must be an eigenstate of the total charge. We regard some pa…
Cluster Property and Robustness of Ground States of Interacting Many Bosons
Akira Shimizu, Takayuki Miyadera
We study spatial correlation functions of local operators of interacting many bosons confined in a box of a large, but volume V, for various `ground states' whose energy densities…