Unraveling the Quantum Mpemba Effect on Markovian Open Quantum Systems

TL;DR

This paper investigates the quantum Mpemba effect in Markovian open quantum systems, revealing mechanisms, scaling behaviors, and subtleties in system-bath interactions that influence the phenomenon.

Contribution

It introduces a physical decoherence-free subspace mechanism, demonstrates exponential decay rate enhancement, and explores the effect through Davies map unravelings and a microscopic bath model.

Findings

Exponential enhancement of decay rates scales with system size.

Decoherence-free subspaces can induce the quantum Mpemba effect.

Choice of figures of merit affects the identification of the effect.

Abstract

In recent years, the quantum Mpemba effect (QME), which occurs when an out-of-equilibrium system reaches equilibrium faster than another that is closer to equilibrium, has attracted significant attention from the scientific community as an intriguing and counterintuitive phenomenon. It generalizes its classical counterpart by extending the concept beyond temperature equilibration. This paper approaches the QME in Markovian open quantum systems from different perspectives. First, we propose a physical mechanism based on decoherence-free subspaces. Second, we show that an exponential enhancement of the decay rate toward equilibrium, scaling with system size, can be obtained, leading to an extreme version of the phenomenon in Markovian open quantum systems. Third, we study the strong Mpemba effect through the unravelings of Davies maps, revealing subtleties in the choice of figures of merit used to identify the QME. Finally, we propose a microscopic model to gain deeper insight into bath dynamics in this context.