Remotely detecting the signal of a local decohering process in spin chains

TL;DR

This paper investigates how signals from local decoherence events in quantum spin chains propagate and can be detected remotely through subsequent measurements, revealing information about the decoherence process.

Contribution

It introduces a method to detect local decoherence in spin chains by analyzing the propagation of signals through different quantum models.

Findings

Signal propagation speed varies with different spin models.

Decoherence signals can be detected remotely at later times.

The method works for both unentangled and entangled initial states.

Abstract

We study the dynamics of a one dimensional quantum spin chain evolving from unentangled or entangled initial state. At a given instant of time a quantum dynamical process (ex. measurement) is performed on a single spin at one end of the chain, decohering the system. Through the further unitary evolution, a signal propagates in the spin chain, which can be detected from a measurement on a different spin at later times. From the dynamical unitary evolution of the decohered state from the epoch time, it is possible to detect the occurrence of the dynamical process. The propagation of the signal for the dynamical process, and the speed of the signal are investigated for various spin models, viz. using the Ising, Heisenberg, and the transverse-XY dynamics.