Single qubit decoherence under a separable coupling to a random matrix environment

TL;DR

This paper investigates how a qubit's coherence is affected by a random matrix environment with separable coupling, revealing unique phenomena like purity oscillations and spectral correlation effects.

Contribution

It introduces an analytical model for qubit decoherence with separable couplings in a random matrix environment, highlighting novel dynamical features.

Findings

Purity oscillations observed in qubit dynamics

Significant effects of spectral correlations on decoherence

Memory effects and symmetry breaking in equilibrium states

Abstract

This paper describes the dynamics of a quantum two-level system (qubit) under the influence of an environment modeled by an ensemble of random matrices. In distinction to earlier work, we consider here separable couplings and focus on a regime where the decoherence time is of the same order of magnitude than the environmental Heisenberg time. We derive an analytical expression in the linear response approximation, and study its accuracy by comparison with numerical simulations. We discuss a series of unusual properties, such as purity oscillations, strong signatures of spectral correlations (in the environment Hamiltonian), memory effects and symmetry breaking equilibrium states.