Urban QKD test for phase and polarization encoding devices

In this work, the results of quantum key distribution through an urban fiber communication line with a length of 30.6km and losses of 11.7dB, obtained by both phase and polarization encoding-based devices, are presented. For phase encoding, a two-pass auto-compensating optical scheme, commonly called “plug&play”, was used. For polarization encoding, a self-developed unconventional optical scheme was made. A continuous key distribution with a sifted key generation rate of 1.0kbit/s and a quantum bit error rate of 5.7% was implemented when using “plug&play” device, whereas 0.1kbit/s and 5.5% was observed when using one with polarization encoding. The features and conveniences of both implementations are discussed.