Real-Time Source-Independent Quantum Random-Number Generator with Squeezed States

Sequences of random numbers are crucial resources for computer simulation and cryptocommunication. Appropriate measurements of the quadratures of a laser's field have been shown to enable efficient generation of high-security, unbiased, truly random numbers. The authors extend this technique to realize a real-time quantum random-number generator, where the source of entropy does not need to be trusted and can be controlled by a malicious third party. By measuring a pair of conjugate quadratures, secure random numbers useful for cryptocommunication can be extracted. The technique is tested on different entropy sources, including thermal and squeezed states of light.