Improving On-Demand Single Photon Source Coherence and Indistinguishability Through a Time-Delayed Coherent Feedback

TL;DR

This paper demonstrates that incorporating time-delayed coherent feedback in a waveguide system can significantly enhance the coherence and indistinguishability of on-demand single photon sources, crucial for quantum information applications.

Contribution

The study introduces a feedback protocol that improves SPS performance by modeling non-Markovian dynamics, achieving up to 57% enhancement in indistinguishability.

Findings

Indistinguishability improved by up to 57% with feedback.

Feedback suppresses off-chip decay and dephasing effects.

Model accurately simulates HBT and HOM interferometers.

Abstract

Single photon sources (SPSs) are an essential resource for many quantum information technologies. We demonstrate how the inclusion of time-delayed coherent feedback in a scalable waveguide system, can significantly improve the two key SPS figures of merit: coherence and indistinguishability. Our feedback protocol is simulated using a quantum trajectory discretized waveguide model which can be used to directly model Hanbury Brown and Twiss (HBT) and Hong-Ou-Mandel (HOM) interferometers. With the proper choice of the round trip phase, the non-Markovian dynamics from the time-delayed feedback improves the indistinguishability of the SPS by up to 57%. We also show how this mechanism suppresses the detrimental effects of off-chip decay and pure dephasing.