We demonstrate the storage and retrieval of an on-demand single photon generated by a collective Rydberg excitation in a low-noise Raman quantum memory located in a different cold atomic ensemble. We generate single photons on demand by exciting a cold cloud of rubidium atoms off resonantly to a Rydberg state, with a generation probability up to 15% per trial. We then show that the single photons can be stored and retrieved with a storage-and-retrieval efficiency of 21% and a low noise floor in the Raman quantum memory. This leads to a signal-to-noise ratio ranging from 11 to 26 for the retrieved single photon, depending on the input-photon-generation probability, which allows us to observe significant antibunching. We also evaluate the performance of the Raman memory as a built-in unbalanced temporal beam splitter, tunable by varying the write-in control-pulse intensity. In addition, we demonstrate that the Raman memory can be used to control the single-photon wave shape. These results are a step forward in the implementation of efficient quantum repeater links using single-photon sources.

• Received 19 November 2021
• Revised 14 June 2022
• Accepted 17 June 2022

DOI:https://doi.org/10.1103/PhysRevApplied.18.024036

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Published by the American Physical Society