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

TL;DR

This paper demonstrates an ultra-low noise quantum memory capable of storing and retrieving on-demand single photons generated via Rydberg excitations, with high efficiency and low noise, advancing quantum repeater technology.

Contribution

The work introduces a highly efficient, low-noise Raman quantum memory for single photons generated by Rydberg collective atomic excitations, enabling improved quantum communication.

Findings

Achieved 21% storage and retrieval efficiency for single photons.

Demonstrated a noise floor of 2.3 x 10^{-4} per trial, enabling high signal-to-noise ratios.

Showed control over photon wave shaping and memory as an unbalanced beam splitter.

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 $p_n= 2.3(3) \times 10^{-4}$ 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 write-in 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.