Probing bath-induced entanglement in a qubit pair by measuring photon correlations

TL;DR

This paper investigates how a shared phonon environment induces entanglement between two un-coupled quantum dot excitons and proposes photon correlation measurements as a way to detect this bath-induced entanglement.

Contribution

It reveals that common phonon interactions can generate steady-state entanglement and suggests photon correlation signatures as evidence of bath-induced quantum correlations.

Findings

Shared phonon environment creates entanglement between quantum dots.

Photon correlations can signal the presence of bath-induced entanglement.

Abstract

Self-assembled quantum dots are ideal structures in which to test theories of open quantum systems: Confined exciton states can be coherently manipulated and their decoherence properties are dominated by interactions with acoustic phonons. We here describe the interaction of a pair of un-coupled, driven, quantum dot excitons with a common phonon environment, and find that this coupling effectively generates two kinds of interaction between the two quantum dots: An elastic coupling mediated by virtual phonons and an inelastic coupling mediated by real phonons. We show that both of these interactions produce steady state entanglement between the two quantum dot excitons. We also show that photon correlations in the emission of the quantum dots can provide a signature of the common environment. Experiments to demonstrate our predictions are feasible with the state-of-the-art technology and would provide valuable insight into quantum dot carrier-phonon dynamics.