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Physica A Statistical Mechanics and its Applications

Work and heat of a quantum system far from its equilibrium state

Yang-Cheng Ye, Hong-Guang Duan, Xian-Ting Liang

Published Jun 1, 2024• 0 citations
Publisher
DOI
10.1016/j.physa.2024.129869

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By computing the local energy expectation values with respect to some local measurement basis we show that for any quantum system there are two fundamentally different contributions: changes in energy that do not alter the local von Neumann entropy and changes that do. We identify the former as work and the latter as heat. Since our derivation makes no assumptions on the system Hamiltonian or its state, the result is valid even for states arbitrarily far from equilibrium. Examples are discussed ranging from the classical limit to purely quantum-mechanical scenarios, i.e. where the Hamiltonian and the density operator do not commute.