Decoherence of a quantum system coupled to an XY spin chain: Role of the initial state of the spin chain

TL;DR

This paper investigates how the initial state of an XY spin chain environment influences the decoherence dynamics of a central quantum spin, revealing Gaussian decay and oscillations under various coupling regimes.

Contribution

It provides a combined analytical and numerical analysis of the decoherence process considering different initial states of the environment, including thermal equilibrium.

Findings

Decoherence exhibits Gaussian decay in both weak and strong coupling regimes.

In strong coupling, the coherence factor oscillates rapidly within a Gaussian envelope.

The initial state of the environment significantly affects the decoherence dynamics.

Abstract

We study the decoherence of a coupled quantum system consisting of a central spin and its correlated environment described by a general $XY$ spin-chain model. We make it clear that the evolution of the coherence factor sensitively depends on the initial states of the environment spin-chain. Specially, the dynamical evolution of the coherence factor of the central spin is numerically and analytically investigated in both weak and strong coupling cases for different initial states including thermal equilibrium state. In both weak and strong coupling regimes, the decay of the coherence factor can be approximated by a Gaussian and in the strong coupling regime the coherence factor oscillate rapidly under a Gaussian envelope. The width of the Gaussian decay (envelope) has been studied in details and we explained the origin of the so-called universal regime.