Thermalisation

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In physics, thermalisation (or thermalization) is the process of physical bodies reaching thermal equilibrium through mutual interaction. In general, the natural tendency of a system is towards a state of equipartition of energy and uniform temperature that maximizes the system's entropy. Thermalisation, thermal equilibrium, and temperature are therefore important fundamental concepts within statistical physics, statistical mechanics, and thermodynamics; all of which are a basis for many other specific fields of scientific understanding and engineering application.

Contents

Examples of thermalisation include:

The hypothesis, foundational to most introductory textbooks treating quantum statistical mechanics, [4] assumes that systems go to thermal equilibrium (thermalisation). The process of thermalisation erases local memory of the initial conditions. The eigenstate thermalisation hypothesis is a hypothesis about when quantum states will undergo thermalisation and why.

Not all quantum states undergo thermalisation. Some states have been discovered which do not (see below), and their reasons for not reaching thermal equilibrium are unclear as of March 2019.

Theoretical description

The process of equilibration can be described using the H-theorem or the relaxation theorem, [5] see also entropy production.

Systems resisting thermalisation

Some such phenomena resisting the tendency to thermalize include (see, e.g., a quantum scar): [6]

Other systems that resist thermalisation and are better understood are quantum integrable systems [19] and systems with dynamical symmetries. [20]

Related Research Articles

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<span class="mw-page-title-main">Quantum chaos</span> Branch of physics seeking to explain chaotic dynamical systems in terms of quantum theory

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<span class="mw-page-title-main">Quantum ergodicity</span>

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<span class="mw-page-title-main">Luttinger's theorem</span>

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<span class="mw-page-title-main">Quantum scar</span>

Quantum scarring refers to a phenomenon where the eigenstates of a classically chaotic quantum system have enhanced probability density around the paths of unstable classical periodic orbits. The instability of the periodic orbit is a decisive point that differentiates quantum scars from the more trivial observation that the probability density is enhanced in the neighborhood of stable periodic orbits. The latter can be understood as a purely classical phenomenon, a manifestation of the Bohr correspondence principle, whereas in the former, quantum interference is essential. As such, scarring is both a visual example of quantum-classical correspondence, and simultaneously an example of a (local) quantum suppression of chaos.

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