Proposal and proof-of-principle demonstration of fast-switching broadband frequency shifting for a frequency-multiplexed quantum repeater

A proposal for fast-switching broadband frequency-shifting technology making use of frequency conversion in a nonlinear crystal is set forth, whereby the shifting imparted to converted photons by creating bank frequency-displaced pump modes that can be selected photonic switch and directed crystal. Proof-of-principle results show expected operation achieved. Even though dimensions currently employed significant excess loss experimental setup prevented single-photon-level inputs, thorough theoretical analysis noise contribution allowed estimation system performance an optimized scenario, where signal-to-noise ratio single-photon reach up 25 dB with proper narrow-band filtering state-of-the-art devices. The proposed solution figures as promising candidate applications frequency-multiplexed quantum repeater architectures output SNR (with 20\% efficiency) capacity 16 channels spread around 100 GHz spectral region.