Terhaar, R.R.TerhaarHäußler, M.M.HäußlerGehring, H.H.GehringWolff, M.M.WolffBeutel, F.F.BeutelWalter, N.N.WalterHartmann, W.W.HartmannTillmann, M.M.TillmannWahl, M.M.WahlRöhlicke, T.T.RöhlickeBülter, A.A.BülterWernicke, D.D.WernickePerlot, NicolasNicolasPerlotRödiger, JasperJasperRödigerSchuck, C.C.SchuckPernice, W.W.Pernice2022-11-082022-11-082022https://publica.fraunhofer.de/handle/publica/42840010.1117/12.26098872-s2.0-85131223205Upcoming quantum technologies require scalable and cost-efficient technical solutions for widespread functionality. In order to exploit the quantum states of light, single-photon detectors are essential for application. Here, we present a low-footprint plug-and-play multi-channel single-photon detector system featuring integrated photonics that allows for ultra-fast quantum key distribution (QKD). Each channel comprises a superconducting nanowire single-photon detector (SNSPD) patterned from a niobium-titanium nitride (NbTiN) superconducting film atop silicon nitride waveguide structures. Subsequently, the on-chip photonics are interfaced by broadband 3D polymeric fiber-to-chip couplers to the ports of an 8x8 fiber array. The readout electronics allow for individual evaluation of up to 64 channels simultaneously. Integrated to a QKD experiment, a pair of the system's detection channels achieves secret key rates of up to 2.5 Mbit/s employing a coherent one-way protocol.enCoherent one-way quantum key distributionMulti-channel single-photon counterMulti-channel single-photon detectorSuperconducting nanowire single photon detectorTime correlated single-photon countingconference paper