Information Transferring Ability of the Different Phases of a finite XXZ Spin Chain

TL;DR

This paper investigates how different phases of a finite XXZ spin chain transmit classical and quantum information, identifying optimal phases for entanglement transfer and revealing unique entanglement flow behaviors.

Contribution

It characterizes the information transfer capabilities of all phases of the XXZ spin chain, highlighting the optimal phase for quantum entanglement transmission and discovering a novel hopping mode of entanglement flow.

Findings

The isotropic antiferromagnetic phase optimally transmits quantum entanglement.

Decoherence shifts the optimal phase to the Neel phase.

A hopping mode of entanglement transfer skips odd sites.

Abstract

We study the transmission of both classical or quantum information through all the phases of a finite XXZ spin chain. This characterizes the merit of the different phases in terms of their ability to act as a quantum wire. As far as quantum information is concerned, we need only consider the transmission of entanglement as the direct transmission of a quantum state is equivalent. The isotropic anti-ferromagnetic spin chain is found to be the optimal point of the phase diagram for the transmission of quantum entanglement when one considers both the amount of transmitted entanglement, as well as the velocity with which it is transmitted. But this optimal point in the phase diagram moves to the Neel phase when decoherence or thermal fluctuations are taken to account. This chain may also be able to transfer classical information even when, due to a large magnitude of the noise, quantum information is not transmitted at all. For a certain range of anisotropies of the model, a curious feature is found in the flow of quantum information inside the chain, namely, a hopping mode of entanglement transfer which skips the odd numbered sites. Our predictions will potentially be testable in several physical systems.