A Random Number Generator Based on Quantum Entangled Photon Pairs

A new scheme for a random number generator based on quantum entangled photon pairs is demonstrated. Signal photons produced by optical parametric down-conversion are detected at two single-photon detectors after transmission or reflection at a 50/50% beamsplitter, to form a truly random binary sequence. Their arrival is signalled by their twin idler photons, so that a cw laser source may be used instead of attenuated laser pulses. Coincidence measurement is employed to obtain the bit sequences, which are shown to fully satisfy the standard tests for randomness.