Semi-device-independent certification of quantum non-Markovianity using sequential Random Access Codes

TL;DR

This paper demonstrates that quantum non-Markovian environments can be semi-device-independently certified through sequential QRACs, showing advantages over Markovian or classical environments in quantum communication tasks.

Contribution

It introduces a semi-device-independent method to certify quantum non-Markovianity using sequential QRACs, highlighting the role of quantum memory in enhancing communication.

Findings

Quantum non-Markovian environments enable quantum advantage in sequential QRACs.

Markovian and classical non-Markovian processes do not provide this advantage.

The method allows certification of quantum non-Markovianity from measurement statistics.

Abstract

The characterization of multi-time correlations in open quantum systems is of fundamental importance. In this work, we investigate multi-time processes using the process matrix formalism and show that the presence of a quantum non-Markovian environment plays a significant role in enhancing the communication capacity in sequential prepare-transform-measure Quantum Random Access Codes (QRAC). The correlated environment enables a quantum advantage to multiple parties, even with projective measurements. In particular, we show that the Markovian and classical non-Markovian processes, i.e. quantum processes with classical feedback from the environment, do not yield sequential quantum advantage. In contrast, it is possible to achieve an advantage in the presence of a quantum non-Markovian environment. Therefore this approach allows a semi-device-independent certification of quantum non-Markovianity. As opposed to entanglement-detection criteria which require the knowledge of the complete process, this method allows to certify the presence of a quantum non-Markovian environment from the observed measurement statistics. Moreover, quantum memory ameliorates the unambiguous certifiable region of unsharp instruments in a semi-device-independent manner.