Single-Photon Detection Technique And Application In Truly Random Number Generator

Quantum cryptography is based on the characteristics of indivisible quanta and entangled systems of quantum mechanics. As it is the application of quantum mechanics at the single photon quantum level, so in quantum cryptography communication the single photon detection technique is the key point in researching. Performance of SPAD (single photon avalanche diode) would be the vital key to decide transmission distance, error rate, and so on . In order to realize the secure cryptosystem a truly random numbers is necessary. Thus the aims of this paper are designing the single photon detector which can work safely and effectively and developing a high quality quantum random numbers generator.After analyzing the characteristics of SPAD (single photon avalanche diode).We discuss many mixed passive and active modes and present an accurate comparison between different circuits after taking into the presence and absence of them. Passive circuit is simple and safe, but it have the drawbacks that are due to the slow recovery from avalanche pulses. Active mode can finish the quenching and reset transitions in short times. At last we find the quenching and reset transition do not necessarily have to be both passive and both active and even a single transition can be managed partly in passive and partly in active ways.A mixed passive-active-quenching and active-reset may be the most suitable and effective approach for our SPAD.In order to reduce the dead time and enhance the counting rate of single photon avalanche detector with higher quantum efficiency , we design a flexible and chronometrical circuit which realizes the excellent active technology with active quenching and fast reset. The detector can work safely and effectively in the active mode and exploit fully the inherent performance of SPAD' s . The experiment results obtained show...