Entangling single photons on a beamsplitter

TL;DR

This paper presents a scheme for creating time-bin entangled states from sequential single photons using a beamsplitter, analyzing the effects of decoherence and how to mitigate them with CQED effects like the Purcell effect.

Contribution

It introduces a quantum mechanical model for time-bin entanglement of sequential photons from quantum dots, including decoherence effects and mitigation strategies.

Findings

Decoherence reduces entanglement visibility in quantum dot sources.

The Purcell effect can restore entanglement visibility.

The scheme enables entanglement generation from single-photon emitters.

Abstract

We report on a scheme for the creation of time-bin entangled states out of two subsequent single photons. Both photons arrive on the same input port of a beamsplitter and the situation in which the photons leave the beamsplitter on different output ports is post-selected. We derive a full quantum mechanical analysis of such time-bin entanglement for emitters subject to uncorrelated dephasing processes and apply this model to sequential single photons emerging from a single semiconductor quantum dot. Our results indicate that the visibility of entanglement is degraded by decoherence effects in the quantum dot, but can be restored by use of CQED effects, namely the Purcell effect.