High-Capacity Angularly Multiplexed Holographic Memory Operating at the Single-Photon Level.

We experimentally demonstrate an angularly multiplexed holographic memory capable of intrinsic generation, storage, and retrieval of multiple photons, based on an off-resonant Raman interaction in warm rubidium-87 vapors. The memory capacity of up to 60 independent atomic spin-wave modes is evidenced by analyzing angular distributions of coincidences between Stokes and time-delayed anti-Stokes light, observed down to the level of single spin-wave excitation during the several-microsecond memory lifetime. We also propose how to practically enhance rates of single- and multiple-photon generation by combining our multimode emissive memory with existing fast optical switches.