Interfacing GHz-bandwidth heralded single photons with a warm vapour Raman memory

Abstract

Photonics is a promising platform for quantum technologies. However, photon\nsources and two-photon gates currently only operate probabilistically.\nLarge-scale photonic processing will therefore be impossible without a\nmultiplexing strategy to actively select successful events. High\ntime-bandwidth-product quantum memories - devices that store and retrieve\nsingle photons on-demand - provide an efficient remedy via active\nsynchronisation. Here we interface a GHz-bandwidth heralded single-photon\nsource and a room-temperature Raman memory with a time-bandwidth product\nexceeding 1000. We store heralded single photons and observe a clear influence\nof the input photon statistics on the retrieved light, which agrees with our\ntheoretical model. The preservation of the stored field's statistics is limited\nby four-wave-mixing noise, which we identify as the key remaining challenge in\nthe development of practical memories for scalable photonic information\nprocessing.\n