Security-Enhanced 10, 118-km Single-Channel 40-Gbit/s Transmission Using PSK Y-00 Quantum Stream Cipher

We demonstrate the first ultra-long haul transmission of Y-00 quantum-noise randomized stream cipher. 40-Gbit/s QPSK signal is encrypted by 216-level phase randomization with a key. Irreducible security based on signal masking by quantum (shot) noise and adequate signal quality after 10, 118-km SMF transmission are achieved.