Quantum Networking II and Quantum Memories

Superradiance has long been understood as a fundamental mechanism underlying the operation of atom-based quantum memories. The collective enhancement and directional emission or ensemble-based memories is key to their excellent performance. In our lab, we operate quantum memories based on laser-cooled rubidium ensembles, with a focus on developing broadband, long-storage time, and efficient memories. We have increased the bandwidth of our fast quantum memory though the principles of superradiance, and explored the system in a related scheme for broadband single-photon emission. In both cases, we implement optimal pulse shaping for the input and control pulses, using the principles of time-reversal to design input pulses that are the time-reverse of superradiant decay. We compare this single-photon emission source to the established DLCZ protocol in terms of the count rates, indistinguishability measures, and efficiency. As a result, these now-broadband single photons are compatible with quantum network operations involving atomic memories. Finally, we consider applying these same principles to alternative geometries beyond the single-trap ensembles to include periodic (lattice) or tweezer trapping.