Single-photon synchronization with a room-temperature atomic quantum memory

TL;DR

This paper demonstrates the synchronization of independent single photons using a room-temperature atomic quantum memory, significantly enhancing photon-pair coincidence rates for quantum information processing.

Contribution

It introduces a method to synchronize single photons with a room-temperature atomic memory, achieving high efficiency and photon indistinguishability.

Findings

End-to-end efficiency of 25% for storing and retrieving photons

Over tenfold increase in photon-pair coincidence rate

Photon indistinguishability verified by Hong-Ou-Mandel interference

Abstract

Efficient synchronization of single photons that are compatible with narrowband atomic transitions is an outstanding challenge, which could prove essential for photonic quantum information processing. Here we report on the synchronization of independently-generated single photons using a room-temperature atomic quantum memory. The photon source and the memory are interconnected by fibers and employ the same ladder-level atomic scheme. We store and retrieve the heralded single photons with end-to-end efficiency of $\eta_\text{e2e}=25\%$ and final anti-bunching of $g^{(2)}_\text{h}=0.023$. Our synchronization process results in over tenfold increase in the photon-pair coincidence rate, reaching a rate of more than $1000$ detected synchronized photon pairs per second. The indistinguishability of the synchronized photons is verified by a Hong-Ou-Mandel interference measurement.