Quantum random number generators are widely used in many applications, ranging from sampling and simulation, fundamental science to cryptography, such as a quantum key distribution system. Among all the previous works, quantum noise from phase fluctuation of laser diodes is one of the most commonly used random source in the quantum random number generation, and many practical schemes based on phase noise with compact systems have been proposed so far. Here, we proposed a new structure of phase noise scheme, utilizing the phase fluctuation from two laser diodes with a slight difference of center wavelength. By analyzing the frequency components and adopting an appropriate band-pass filter, we prove that our scheme extracts quantum noise and filtered other classical noises substantially. Results of a randomness test shows that the extracted random sequences are of good performance. Due to lack of delay-line and the low requirement on other devices in this system, our scheme is promising in future scenarios for miniaturized quantum random number generation systems.
Random number generation by coherent detection of quantum phase noise