Non-Markovian dynamics in two-qubit dephasing channels with an application to superdense coding

TL;DR

This paper compares two measures of non-Markovianity in two-qubit dephasing channels, demonstrating their effectiveness in detecting memory effects and optimizing superdense coding performance under noise.

Contribution

It introduces a comparative analysis of non-Markovianity measures in two-qubit channels and applies findings to enhance superdense coding under noise conditions.

Findings

Trace distance detects local non-Markovianity effectively.

Channel capacity measure identifies global memory effects.

Optimal noise configuration maximizes information transmission.

Abstract

We study the performance of two measures of non-Markovianity in detecting memory effects in two-qubit dephasing channels. By combining independent Markovian and non-Markovian noise on the qubits, our results show that the trace distance measure is able to detect the memory effects when at least one of the local channels displays non-Markovianity. A measure based on channel capacity, in turn, becomes non-zero when the global two-qubit dynamics shows memory effects. We apply these schemes to a well-known superdense coding protocol and demonstrate an optimal noise configuration to maximize the information transmission with independent local noises.