Manuscript accepted for publication in Light: Science & Applications

The manuscript ‘High-rate intercity quantum key distribution with a semiconductor single-photon source’ has been accepted for publication in Light: Science & Applications.

In this manuscript, the authors report the first intercity QKD experiment with a deterministic single-photon source. A circular Bragg grating (CBG) containing a semiconductor QD, is efficiently emitting high-purity single photons in the telecommunication C-band in conjunction with polarisation encoding in the standard QKD protocol. The photons are then sent through a 79 km long dark fibre between two German cities of Hannover and Braunschweig, featuring a loss of (25.49 ± 0.02) dB corresponding to a standard telecom fibre length of 130.32 km. At the other end of the fibre, Physikalisch-Technische Bundesanstalt, we verify that high-rate secret key transmission and a low quantum bit error ratio (QBER) are ensured for 35 hours. In addition, positive key rates are determined achievable for distances up to 144 km corresponding to 28.11 dB loss in the laboratory. The reported result surpasses all current telecom SPS-based QKD implementations in terms of the achieved secret key rate. The high transmission rate of quantum keys through a deployed fibre, enabled by the high-brightness emission from semiconductor QD, demonstrates the feasibility of incorporating semiconductor SPSs into real-world quantum communication scenarios.