Fast, noise-free atomic optical memory with 35-percent end-to-end efficiency

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