This paper demonstrates Hong-Ou-Mandel (HOM) interference between single-photon-level pulses stored and retrieved from independent room-temperature quantum memories. The study shows that storage and retrieval do not significantly degrade HOM visibility for few-photon-level polarization states in a dual-rail configuration. For single-photon-level pulses, HOM visibility is measured with varying background levels, revealing a dependence on the signal-to-background ratio. A visibility of 43% is achieved, suggesting a potential 33% visibility for polarization qubits. These findings pave the way for large-scale memory-assisted quantum networks.

Sonali Gera, Chase Wallace, Mael Flament, Alessia Scriminich, Mehdi Namazi, Youngshin Kim, Steven Sagona-Stophel, Giuseppe Vallone, Paolo Villoresi, Eden Figueroa