A Study Of Quantum Random Number Generator And Quantum Secure Direct Communication In A Noisy Channel

In the article we analyzed some present quantum random number generator based on photons, and then present a realization of a physical quantum random number generator based on the process of splitting a beam of photons on a beam splitter. By utilizing either a beamsplitter, single photon detectors and high speed electronics the presented device is capable of generating a continuous stream of binary random numbers at a rate of 100Kbit/s. The randomness of the generated numbers is shown by running several random tests to be very well. At last, several disadvantages and some possible improvement are presented. The rate will be even higher if we use a higher modulating frequency, as the generating rate will be determined by the detecting efficiency and dead time of the single photon detector.The quantum secure direct communication is a recently proposed novel quantum communication scheme. As it needs to transmit information directly, the loss of quantum channel leads to an irretrievable particle loss as well as information. In this paper, the loss of quantum channel is analyzed and a method is put forward to recover the particle and information loss effectively using universal quantum error correction Then a secure direct communication scheme is proposed, in a loss channel the information that eavesdropper can get would be limited to arbitrarily small when the code is properly chosen and the correction operation is properly arranged.