Tracing Information Flow from Open Quantum Systems

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, photons are used 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, different types of information transfer are analyzed. Extending the usual perspective which is focused on the system alone, the presence of information is also investigated in the environment.