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We describe a method to compute thermodynamic quantities in the harmonic approximation for identical bosons and fermions in an external confining field. We use the canonical partition function where only energies and their degeneracies…

Quantum Physics · Physics 2012-02-16 J. R. Armstrong , N. T. Zinner , D. V. Fedorov , A. S. Jensen

In this work, we present a compact analytical approximation for the quantum partition function of systems composed of quantum oscillators. The proposed formula is general and applicable to an arbitrary number of oscillators described by a…

Statistical Mechanics · Physics 2025-07-08 Michel Caffarel

Critical phenomena at finite temperature underpin a broad range of physical systems, yet their study remains challenging due to computational bottlenecks near phase transitions. Quantum annealers have attracted significant interest as a…

Statistical Mechanics · Physics 2025-07-11 Gianluca Teza , Francesco Campaioli , Marco Avesani , Oren Raz

By leveraging the Variational Quantum Eigensolver (VQE), the ``quantum equation of motion" (qEOM) method established itself as a promising tool for quantum chemistry on near term quantum computers, and has been used extensively to estimate…

Quantum Physics · Physics 2024-09-04 Daniele Morrone , N. Walter Talarico , Marco Cattaneo , Matteo A. C. Rossi

Linearizing the appropriate kinetic equation we derive general response functions including selfconsistent mean fields or density functionals and collisional dissipative contributions. The latter ones are considered in relaxation time…

Nuclear Theory · Physics 2008-12-18 Klaus Morawetz , Uwe Fuhrmann

In this article, we propose a novel method for sampling potential functions based on noisy observation data of a finite number of observables in quantum canonical ensembles, which leads to the accurate sampling of a wide class of test…

Numerical Analysis · Mathematics 2020-04-08 Ziheng Chen , Zhennan Zhou

We consider statistical methods based on finite samples of locally randomized measurements in order to certify different degrees of multiparticle entanglement in intermediate-scale quantum systems. We first introduce hierarchies of…

Quantum Physics · Physics 2023-06-08 Andreas Ketterer , Satoya Imai , Nikolai Wyderka , Otfried Gühne

Measurement-based quantum computation utilizes an initial entangled resource state and proceeds with subsequent single-qubit measurements. It is implicitly assumed that the interactions between qubits can be switched off so that the…

Quantum Physics · Physics 2011-08-08 Ying Li , Daniel E. Browne , Leong Chuan Kwek , Robert Raussendorf , Tzu-Chieh Wei

This paper investigates a new formalism to describe real time evolution of quantum systems at finite temperature. A time correlation function among subsystems will be derived which allows for a probabilistic interpretation. Our derivation…

High Energy Physics - Theory · Physics 2009-10-31 E. Mendel , M. Nest

We consider the problem of estimating the partition function of the ferromagnetic Ising model in a consistent external magnetic field. The estimation is done via importance sampling in the dual of the Forney factor graph representing the…

Computation · Statistics 2017-01-27 Mehdi Molkaraie

Attempts to understand zero temperature phase transitions have forced physicists to consider a regime where the standard paradigms of condensed matter physics break down [1-4]. These quantum critical systems lack a simple description in…

Quantum Gases · Physics 2012-07-04 Kaden R. A. Hazzard , Erich J. Mueller

We investigate the equilibration and thermalization properties of quantum systems interacting with a finite dimensional environment. By exploiting the concept of time averaged states, we introduce a completely positive map which allows to…

Quantum Physics · Physics 2012-11-27 A. Smirne , E. -M. Laine , H. -P. Breuer , J. Piilo , B. Vacchini

We discuss an approach to determine averages of the work, dissipated heat and variation of internal energy of an open quantum system driven by an external classical field. These quantities are measured by coupling the quantum system to a…

Quantum Physics · Physics 2022-03-23 Paolo Solinas , Mirko Amico , Nino N. Zanghì

Quantum measurements are basic operations that play a critical role in the study and application of quantum information. We study how the use of quantum, coherent, and classical thermal states of light in a circuit quantum electrodynamics…

We derive the semiclassical series for the partition function in Quantum Statistical Mechanics (QSM) from its path integral representation. Each term of the series is obtained explicitly from the (real) minima of the classical action. The…

Quantum Physics · Physics 2009-10-31 C. A. A. de Carvalho , R. M. Cavalcanti

Efficient and accurate algorithm for partition function, free energy and thermal entropy calculations is of great significance in statistical physics and quantum many-body physics. Here we present an unbiased but low-technical-barrier…

Statistical Mechanics · Physics 2024-11-19 Yi-Ming Ding , Jun-Song Sun , Nvsen Ma , Gaopei Pan , Chen Cheng , Zheng Yan

We investigate the measurements of two-state quantum systems (qubits) at finite temperatures using a resonant harmonic oscillator as a quantum probe. The reduced density matrix and oscillator correlators are calculated by a scheme combining…

Mesoscale and Nanoscale Physics · Physics 2009-11-11 Teemu Ojanen , Tero T. Heikkila

We present an efficient way to compute diagonal and off-diagonal n-point correlation functions for quantum spin-systems within the loop algorithm. We show that the general rules for the evaluation of these correlation functions take an…

Condensed Matter · Physics 2009-10-31 J. V. Alvarez , Claudius Gros

We study the heat statistics of a quantum Brownian motion described by the Caldeira-Leggett model. By using the path integral approach, we introduce a novel concept of the quantum heat functional along every pair of Feynman paths. This…

Statistical Mechanics · Physics 2018-07-18 Ken Funo , H. T. Quan

Accurately evaluating finite-temperature properties of quantum many-body systems remains a central challenge. Many existing quantum approaches typically require thermal-state preparation at each target temperature, making low-temperature…

Quantum Physics · Physics 2026-04-15 Hiroto Yamamoto , Katsuhiro Morita