An intuitive scheme for the restoration of entanglement for polarization-entangled photons emitted from quantum dots with non-vanishing fine structure splitting

TL;DR

This paper proposes a simple, practical method to restore entanglement in polarization-entangled photons emitted from quantum dots affected by fine structure splitting, using time-dependent operations on the photons rather than on the emitter.

Contribution

It introduces a novel scheme for entanglement restoration that acts on emitted photons, contrasting with traditional methods targeting the quantum dot itself.

Findings

The scheme effectively restores entanglement despite fine structure splitting.

The proposed method is feasible with current technology.

The robustness of the scheme is confirmed through Monte Carlo simulations.

Abstract

Generation of polarization-entangled photons from quantum dots via the biexciton-exciton recombination cascade is complicated by the presence of an energy spitting between the intermediate excitonic levels, which severely degrades the quality of the entangled photon source. In this paper we present a novel, conceptually simple and straightforward proposal for restoring the entanglement of said source by applying a cascade of time-dependent operations on the emitted photons. This is in striking contrast with the techniques usually employed, that act on the quantum emitter itself in order to remove the fine structure splitting at its root. The feasibility of the implementation with current technology is discussed, and the robustness of the proposed compensation scheme with respect to imperfections of the experimental apparatus is evaluated via a series of Monte Carlo simulations.