Open Quantum Dynamics: Memory Effects and Superactivation of Backflow of Information

TL;DR

This paper explores how memory effects in open quantum systems can be superactivated through tensor product dynamics, leading to backflow of information that is not present in individual subsystems.

Contribution

It introduces the concept of superactivation of backflow of information in composite quantum systems and analyzes the divisibility properties of their dynamical maps.

Findings

Memory effects can be superactivated in tensor product dynamics.

Backflow of information can occur in the combined system without individual subsystems exhibiting it.

The study provides insights into non-Markovian behavior in open quantum systems.

Abstract

We investigate the divisibility properties of the tensor products $\Lambda^{(1)}_t\otimes\Lambda^{(2)}_t$ of open quantum dynamics $\Lambda^{(1,2)}_t$ with time-dependent generators. These dynamical maps emerge from a compound open system $S_1+S_2$ that interacts with its own environment in such a way that memory effects remain when the environment is traced away. This study is motivated by the following intriguing effect: one can have Backflow of Information (BFI) from the environment to $S_1+S_2$ without the same phenomenon occurring for either $S_1$ and $S_2$. We shall refer to this effect as the Superactivation of BFI (SBFI).