R&D: Fast, Noise-Free Atomic Optical Memory with 35% End-to-End Efficiency

Communications Physics has published an article written by Omri Davidson, Ohad Yogev, Eilon Poem, and Ofer Firstenberg, Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot, 7610001, Israel.

Abstract: “Coherent optical memories will likely play an important role in future quantum communication networks. Among the different platforms, memories based on ladder-type orbital transitions in atomic gasses offer high bandwidth (>100 MHz), continuous (on-demand) readout, and low-noise operation. Here we report on an upgraded setup of our previously-reported fast ladder memory, with improved efficiency and lifetime, and reduced noise. The upgrade employs a stronger control field, wider signal beam, reduced atomic density, higher optical depth, annular optical-pumping beam, and weak dressing of an auxiliary orbital to counteract residual Doppler-broadening. For a 2 ns-long pulse, we demonstrate 53% internal efficiency, 35% end-to-end efficiency, 3 × 10⁻⁵ noise photons per pulse, and a 1/e lifetime of 108 ns. This combination of performances is a record for continuous-readout memories.“