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We propose incorporating multi-qubit nonunitary operations in Variational Quantum Thermalizers (VQTs). VQTs are hybrid quantum-classical algorithms that generate the thermal (Gibbs) state of a given Hamiltonian, with applications in quantum…

Quantum Physics · Physics 2025-03-28 Elias Zapusek , Kristina Kirova , Walter Hahn , Michael Marthaler , Florentin Reiter

In the framework of the theory of open systems based on completely positive quantum dynamical semigroups, we give a description of continuous variable quantum entanglement and quantum discord for a system consisting of two non-interacting…

Quantum Physics · Physics 2015-06-12 Aurelian Isar

The performance of a radiatively cooled instrument is investigated in the context of optomechanical quantum experiments, where the environment of a macroscopic particle in a quantum-superposition has to be cooled to less than 20\,K in deep…

The resource theory of thermal operations, an established model for small-scale thermodynamics, provides an extension of equilibrium thermodynamics to nonequilibrium situations. On a lattice of any dimension with any translation-invariant…

Open quantum systems are studied from the thermodynamical point of view unifying the principle of maximum informational entropy and the hypothesis of relaxation times hierarchy. The result of the unification is a non-Markovian and local in…

Quantum Physics · Physics 2014-11-24 Vitalii Semin , Francesco Petruccione

We have developed a theoretical formalism to introduce temperature as a parameter into the framework of non-relativistic quantum mechanics using the laws of classical thermodynamics and the canonical ensemble scheme of statistical…

Quantum Physics · Physics 2021-03-08 Ashkan Shekaari , Mahmoud Jafari

Cooling quantum systems is arguably one of the most important thermodynamic tasks connected to modern quantum technologies and an interesting question from a foundational perspective. It is thus of no surprise that many different…

Lossy bosonic channels play an important role in a number of quantum information tasks, since they well approximate thermal dissipation in an experiment. Here, we characterize their metrological power in the idler-free and…

Quantum Physics · Physics 2022-09-14 Robert Jonsson , Roberto Di Candia

In this work we present a formalism to describe non equilibrium conditions in systems with a discretized energy spectrum, such as quantum systems. We develop a formalism based on a combination of Gibbs-Shannon entropy and information…

Statistical Mechanics · Physics 2013-07-23 Alessio Gagliardi , Alessandro Pecchia , Aldo Di Carlo

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

Emulating thermal observables on a digital quantum computer is essential for quantum simulation of many-body physics. However, thermalization typically requires a large system size due to incorporating a thermal bath, whilst limited…

Quantum Physics · Physics 2025-03-12 H. Perrin , T. Scoquart , A. I. Pavlov , N. V. Gnezdilov

Algorithmic cooling can be used to find correlated states of many-body quantum systems. It is based on quantum circuits that perform nonunitary operations, whose implementation can be challenging on near-term quantum computers. In this work…

Quantum thermodynamics aims at investigating both the emergence and the limits of the laws of thermodynamics from a quantum mechanical microscopic approach. In this scenario, thermodynamic processes with no heat exchange, namely, adiabatic…

We study optimal control strategies to optimize the relaxation rate towards the fixed point of a quantum system in the presence of a non-Markovian dissipative bath. Contrary to naive expectations that suggest that memory effects might be…

Preparing thermal states on a quantum computer can have a variety of applications, from simulating many-body quantum systems to training machine learning models. Variational circuits have been proposed for this task on near-term quantum…

Quantum Physics · Physics 2021-11-09 Jonathan Foldager , Arthur Pesah , Lars Kai Hansen

The treatment of quantum thermodynamic systems beyond weak coupling is of increasing relevance, yet extremely challenging. The evaluation of thermodynamic quantities in strong-coupling regimes requires a nonperturbative knowledge of the…

Quantum Physics · Physics 2025-01-16 Francesco Albarelli , Bassano Vacchini , Andrea Smirne

We combine the formalisms of diagonal entropy and Jarzynski Equality to study the thermodynamic properties of closed quantum systems. Applying this approach to a quantum harmonic oscillator, the diagonal entropy offers a notion of…

Quantum Physics · Physics 2013-07-09 Van A. Ngo , Stephan Haas

A quantum system coupled to a bath at some fixed, finite temperature converges to its Gibbs state. This thermalization process defines a natural, physically-motivated model of quantum computation. However, whether quantum computational…

Quantum Physics · Physics 2025-01-15 Thiago Bergamaschi , Chi-Fang Chen , Yunchao Liu

Proving thermalization from the unitary evolution of a closed quantum system is one of the oldest questions that is still nowadays only partially resolved. Several efforts have led to various formulations of what is called the eigenstate…

Quantum Physics · Physics 2025-07-24 Christian Bertoni , Clara Wassner , Giacomo Guarnieri , Jens Eisert

Optically trapped nanoparticles have recently emerged as exciting candidates for tests of quantum mechanics at the macroscale and as versatile platforms for ultrasensitive metrology. Recent experiments have demonstrated parametric feedback…

Quantum Physics · Physics 2016-03-23 B. Rodenburg , L. P. Neukirch , A. N. Vamivakas , M. Bhattacharya