Generating long-distance magnetic couplings with flat bands

TL;DR

This paper demonstrates that flat bands in spin chains can induce long-distance magnetic couplings, potentially enabling long-range quantum communication by linking flat band properties with quantum metrics.

Contribution

It reveals that flat bands can facilitate long-range magnetic interactions in spin chains, connecting flat band eigenstates' quantum metric to coupling lengthscale.

Findings

Flat bands enable long-distance magnetic couplings.

Coupling lengthscale relates to the quantum metric.

Potential for long-distance quantum communication.

Abstract

One of the great challenges for the large-scale development of quantum technologies is to generate and control the entanglement of quantum bits through interactions of sufficiently long range. Two decades ago, spin chains have been proposed for quantum communication. Unfortunately, couplings are of very short range in general which drastically limits the communication to very short distances. Here, we demonstrate that the presence of flat bands (FBs) can trigger very long-distance magnetic couplings in spin chains. Furthermore, we show that the typical decaying lengthscale is directly related to the quantum metric of the flat band eigenstates. We believe that our unexpected findings could open up an alternative route to enable long-distance quantum communication.