Tracing Information Flow from Open Quantum Systems

TL;DR

This paper investigates how information flows between a qubit and its environment in open quantum systems using photon-based quantum simulations, highlighting the role of non-classical correlations and environment information.

Contribution

It introduces a quantum simulation approach to study information transfer in open quantum systems, emphasizing the environment's role often overlooked in traditional analyses.

Findings

Information transfer varies with system-environment coupling

Trace distance effectively measures information flow

Environment can store and reveal information about the system

Abstract

Open quantum systems are highly relevant, both for practical applications as well as for fundamental questions about the nature of information and its transfer, encompassing for example decoherence and memory effects. Quantum mechanics introduces additional complexity to the transfer of information, e.g., storage of information in non-classical correlations. Yet, some of these aspects tend to be neglected by the usual framework of open system research. In this work we use photons in a waveguide array to implement a quantum simulation of the coupling of a qubit with a low-dimensional discrete environment. Using the trace distance between quantum states as a measure of information, we analyze different types of information transfer. Extending the usual perspective which is focused on the system alone, we also investigate the presence of information in the environment.