Vacuum-based quantum random number generator using multi-mode coherent states

We present an optical quantum random number generator based on vacuum fluctuation measurements that uses multi-mode coherent states generated by electro-optical phase modulation of an intense optical carrier. In this approach the weak coherent multi-mode state (or a vacuum state) interferes with the carrier, which acts as a local oscillator, on each side mode independently. The proposed setup can effectively compensate for any deviations between the two arms of a balanced detector by controlling the modulation index of the modulator. We perform a proof-of-principle experiment and demonstrate random number generation with a possibility of real-time randomness extraction at the rate of 400 Mbit/s. The proposed concept has a potential for randomness generation rates comparable to the widely employed vacuum-based quantum random number generators.