Irreversible processes without energy dissipation in an isolated Lipkin-Meshkov-Glick model

TL;DR

This paper demonstrates that in certain isolated quantum systems, irreversible processes can occur without energy dissipation, involving symmetry-breaking and information loss, supported by numerical analysis of the Lipkin-Meshkov-Glick model.

Contribution

It reveals a class of irreversible quantum processes without energy dissipation, highlighting the role of symmetry and information loss in isolated systems.

Findings

Irreversible processes without energy dissipation are possible in isolated quantum systems.

Symmetry-breaking observables change after a closed cycle, indicating irreversibility.

Von Neumann entropy increases, confirming information loss during the process.

Abstract

For a certain class of isolated quantum systems, we report the existence of irreversible processes in which the energy is not dissipated. After a closed cycle in which the initial energy distribution is fully recovered, the expectation value of a symmetry-breaking observable changes from a value different from zero in the initial state, to zero in the final state. This entails the unavoidable loss of a certain amount of information, and constitutes a source of irreversibility. We show that the von Neumann entropy of time-averaged equilibrium states increases in the same magnitude as a consequence of the process. We support this result by means of numerical calculations in an experimentally feasible system, the Lipkin-Meshkov-Glick model.