Ultra-low noise quantum memory for quasi-deterministic single photons generated by Rydberg collective atomic excitations

Abstract

We demonstrate the storage and retrieval of an on-demand single photon generated by a collective Rydberg excitation in an ultra-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 an efficiency of 21 % and a noise floor of pn = 2.3(3) × 10 −4 per trial 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 performances of the Raman memory as built-in unbalanced temporal beam splitter, tunable by varying the writein control pulse intensity. In addition, we demonstrate that the Raman memory can be used to control the single-photon waveshape. These results are a step forward in the implementation of efficient quantum-repeater links using single-photon sources.

Efficient, ever-ready quantum memory at room temperature for single photons

“…But weak coherent states cannot replace single photons for applications such as photonic quantum computation [18], and physics at the quantum limit may exhibit fundamentally different interactions [19,20]. Hence operation with tailored quantum light sources is vital for real-world relevant benchmarking of quantum memories [21][22][23]. To date the most efficient realisations employed electromagnetically induced transparency in a rubidium magneto-optical trap (MOT) for the memory and fourwave mixing or spontaneous Raman scattering in a separate cold atomic ensemble as the single photon source [24,25].…”