Decoherence as attenuation of mesoscopic echoes in a spin-chain channel

TL;DR

This paper investigates how decoherence manifests as the attenuation of mesoscopic echoes in a spin-chain quantum channel, using a model of two weakly coupled spin chains to quantify environmental effects.

Contribution

It introduces a method to quantify decoherence in a quantum channel via mesoscopic echo attenuation in a spin-ladder system, linking many-body dynamics to a one-body decoherence rate.

Findings

Decoherence rates depend on amplitude fluctuation and dephasing ratios.

Mesoscopic echoes decay exponentially with a rate given by Fermi golden rule.

The model effectively describes environment-induced decoherence in spin chains.

Abstract

An initial local excitation in a confined quantum system evolves exploring the whole system, returning to the initial position as a mesoscopic echo at the Heisenberg time. We consider a two weakly coupled spin chains, a spin ladder, where one is a quantum channel while the other represents an environment. We quantify decoherence in the quantum channel through the attenuation of the mesoscopic echoes. We evaluate decoherence rates for different ratios between sources of amplitude fluctuation and dephasing in the inter-chain interaction Hamiltonian. The many-body dynamics is seen as a one-body evolution with a decoherence rate given by the Fermi golden rule.