Publications associated with Ultrafast quantum optics and optical metrology

Raman quantum memory with built-in suppression of four-wave-mixing noise

Physical Review A American Physical Society 100 (2019) 033801

Thomas, T Hird, J Munns, B Brecht, D Saunders, J Nunn, IA Walmsley, PM Ledingham

Quantum memories are essential for large-scale quantum information networks. Along with high efficiency, storage lifetime, and optical bandwidth, it is critical that the memory adds negligible noise to the recalled signal. A common source of noise in optical quantum memories is spontaneous four-wave mixing. We develop and implement a technically simple scheme to suppress this noise mechanism by means of quantum interference. Using this scheme with a Raman memory in warm atomic vapor, we demonstrate over an order of magnitude improvement in noise performance. Furthermore we demonstrate a method to quantify the remaining noise contributions and present a route to enable further noise suppression. Our scheme opens the way to quantum demonstrations using a broadband memory, significantly advancing the search for scalable quantum photonic networks.

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