Enhanced quantum transport in chiral quantum walks

TL;DR

This paper investigates how chiral quantum walks can enhance quantum transport on chain-like graphs by optimizing phases and topologies, identifying structures with significantly improved transport efficiency.

Contribution

It introduces criteria for quantum transport enhancement and demonstrates how to optimize chiral quantum walks for better transport on complex graph structures.

Findings

Two structures show true chiral quantum walk behavior with improved transport.

One structure reduces to a weighted line with minor couplings.

Chiral phases can significantly increase long-chain transport probability.

Abstract

Quantum transport across discrete structures is a relevant topic of solid state physics and quantum information science, which can be suitably studied in the context of continuous-time quantum walks. The addition of phases degrees of freedom, leading to chiral quantum walks, can also account for directional transport on graphs with loops. We discuss criteria for quantum transport and study the enhancement that can be achieved with chiral quantum walks on chain-like graphs, exploring different topologies for the chain units and optimizing over the phases. We select three candidate structures with optimal performance and investigate their transport behaviour with Krylov reduction. While one of them can be reduced to a weighted line with minor couplings modulation, the other two are truly chiral quantum walks, with enhanced transport probability over long chain structures.