Two-Photon Interference of Single Photons from Dissimilar Sources

TL;DR

This paper develops a theoretical framework for analyzing two-photon interference between dissimilar quantum light sources, crucial for hybrid quantum networks, and assesses how various system parameters affect photon indistinguishability.

Contribution

It introduces a comprehensive model for pulsed two-photon interference from dissimilar sources, accounting for real-world imperfections and guiding hybrid quantum system design.

Findings

Optimal emitter lifetime for maximum indistinguishability identified.

Impact of spectral detuning, jitter, and dephasing quantified.

Comparison of different hybrid quantum emitter combinations provided.

Abstract

Entanglement swapping and heralding are at the heart of many protocols for distributed quantum information. For photons, this typically involves Bell state measurements based on two-photon interference effects. In this context, hybrid systems that combine high rate, ultra-stable and pure quantum sources with long-lived quantum memories are particularly interesting. Here, we develop a theoretical description of pulsed two-photon interference of photons from dissimilar sources to predict the outcomes of second-order cross-correlation measurements. These are directly related to, and hence used to quantify, photon indistinguishability. We study their dependence on critical system parameters such as quantum state lifetime and frequency detuning, and quantify the impact of emission time jitter, pure dephasing and spectral wandering. Our results show that for fixed lifetime of emitter one, for each frequency detuning there is an optimal lifetime of emitter two that leads to highest photon indistinguishability. Expectations for different hybrid combinations involving III-V quantum dots, color centers in diamond, 2D materials and atoms are quantitatively compared for real-world system parameters. Our work both provides a theoretical basis for the treatment of dissimilar emitters and enables assessment of which imperfections can be tolerated in hybrid photonic quantum networks.