Memory effects in a Markov chain dephasing channel

TL;DR

This paper investigates how memory effects in a Markov chain dephasing channel influence quantum error correction, showing that even weak memory can harm performance but can also be exploited for better protection.

Contribution

It introduces a model of a dephasing channel with memory and analyzes its impact on quantum error correction, highlighting both challenges and opportunities.

Findings

Weak memory effects degrade error correction performance.

Memory can be exploited to improve quantum information protection.

Memory effects are significant even at low levels.

Abstract

We study a dephasing channel with memory, modelled by a Markov chain. We show that even weak memory effects have a detrimental impact on the performance of quantum error correcting schemes designed for uncorrelated errors. We also discuss an alternative scheme that takes advantage of memory effects to protect quantum information.