Probing quantum chaos with the entropy of decoherent histories

TL;DR

This paper introduces a novel approach to defining and detecting quantum chaos by analyzing the entropy of decoherent histories in an open quantum system, bridging classical and quantum chaos concepts.

Contribution

It proposes using the entropy of decoherent histories as a universal criterion for quantum chaos, demonstrated through the quantum kicked top model with environmental interactions.

Findings

Entropy production differs significantly between integrable and chaotic regimes.

Decoherent history entropy serves as a quantum chaos indicator.

Model illustrates the classical-quantum correspondence in chaos detection.

Abstract

Quantum chaos, a phenomenon that began to be studied in the last century, still does not have a rigorous understanding. By virtue of the correspondence principle, the properties of the system that lead to chaotic dynamics at the classical level must also be present in the underlying quantum system. In the classical case, the exponential divergence of nearby trajectories in time is described in terms of the Lyapunov exponent. However, in the quantum case, a similar description of chaos is, strictly speaking, impossible due to absence of trajectories. There are different approaches to remedy this situation, but the universal criterion of quantum chaos is absent. We propose the quantum chaos definition in the manner similar to the classical one using decoherent histories as a quantum analogue of trajectories. For this purpose, we consider the model of an open quantum kicked top interacting with the environment, which is a bosonic bath, and illustrate this idea. Here, the environment plays the role of a trajectory recording device. For the kicked top model at the classical level, depending on the kick strength, crossover occurs between the integrable and chaotic regimes. We show that for such a model, the production of entropy of decoherent histories is radically different in integrable and chaotic regimes. Thus, the entropy of an ensemble of quantum trajectories can be used as a signature of quantum chaos.