Quantum key distribution over 100 km of underwater optical fiber assisted by a fast-gated single-photon detector

Quantum key distribution over 100 km of underwater optical fiber assisted by a fast-gated single-photon detector

In this work, we implemented a quantum key distribution link between Sicily (Italy) and Malta utilizing two different single-photon avalanche diode (SPAD) detectors. The performances of a standard commercial SPAD have been compared with the results achieved with an alternative prototype of fast-gated system in a package (SIP) SPAD; the SIP detector has shown to be able to accomplish a 14 times higher key rate compared with the commercial device over the channel showing 20 dB of losses.