Interfacing GHz-bandwidth heralded single photons with a room-temperature Raman quantum memory

TL;DR

This paper demonstrates the integration of a GHz-bandwidth heralded single-photon source with a room-temperature Raman quantum memory, achieving high time-bandwidth product storage and highlighting noise challenges for scalable photonic quantum computing.

Contribution

It presents the first interface of a GHz-bandwidth single-photon source with a room-temperature quantum memory exceeding a 1000 time-bandwidth product, advancing scalable photonic quantum technologies.

Findings

Successful storage of heralded single photons in a room-temperature Raman memory.

Input photon statistics influence the retrieved light, confirming theoretical predictions.

Four-wave-mixing noise limits the preservation of photon statistics.

Abstract

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