Semi-quantum noise randomized data encryption based on an amplified spontaneous emission light source

The first semi-quantum noise randomized cipher based on amplified spontaneous emission (ASE) light source employing Y-00 protocol is proposed and demonstrated by a proof-of-principle experiment. As the signal carrier, ASE light can provide another fundamental uncertainty, namely, self-beating noise of ASE signal, which is much bigger than quantum shot noise of mesoscopic coherent state and also inevitable. By incorporating both the shot noise and beat noise of ASE signals, the security will be improved with a larger number of masked signals (NMS) under intrinsic noise. After formulating NMS and Q-factor in theory, we investigate the impacts of key system parameters on the security and transmission performances, respectively, in order to optimize the system design. To evidence the theoretical results, an experimental setup with balanced photodetector (BPD) as decoder is constructed. The local light modulated by M/2-ary running key is applied as optical threshold signal, which is fed into BPD together with the M-ary ASE signal, outputting the binary signal. Eventually, a 128-level Y-00 realization based on ASE source is realized at 2.5Gb/s over 100-km fiber. The experimental results agree with the theory in the trend, which indicate the validity and feasibility of the proposed scheme.