Quantum Interference between Autonomous Single-Photon Sources from Doppler-Broadened Atomic Ensemble

TL;DR

This paper demonstrates high-visibility quantum interference between two autonomous, bright single-photon sources generated from Doppler-broadened rubidium atoms, advancing practical quantum network development.

Contribution

It experimentally achieves Hong-Ou-Mandel interference between independent autonomous photon sources without synchronization, using Doppler-broadened atomic ensembles.

Findings

83% HOM dip visibility achieved

5000 four-fold coincidence events per hour

Interference demonstrated without additional filters or synchronization

Abstract

To realize a quantum network based on quantum entanglement swapping, bright and completely autonomous sources are essentially required. Here, we experimentally demonstrate Hong-Ou-Mandel (HOM) quantum interference between two independent bright photon pairs generated via the spontaneous four-wave mixing in Doppler-broadened ladder-type 87Rb atoms. Bright autonomous heralded single photons are operated in a continuous-wave (CW) mode with no synchronization or supplemental filters. The four-fold photon coincidence counts per hour correspond to 5000 events for a temporal range of 10 ns, one order higher than those of previously reported for autonomous single photons. We observe an HOM dip with 83% visibility with the two autonomous heralded single photons for an effective measurement time of 900 s. The achievement of the HOM interference between the two bright autonomous photon-pair sources has made an important step towards a practical scalable quantum network.