Genuine randomness from an incoherent source
Bing Qi · arXiv (Cornell University) · 2016
Quantum random number generators (QRNGs) harness the intrinsic randomness in measurement processes: the measurement outputs are truly random given the input state is a superposition of the eigenstates of the measurement operators. We show in the case of trusted devices, genuine randomness could be generated even when the input to the detector is a mixed state. We propose a random number generation scheme based on measuring the quadrature fluctuations of a single mode thermal state with an optical homodyne detector. By interfering a broadband incoherent source with a single mode local oscillator at a beam splitter and performing differential photodetection, we can selectively detect the quadrature fluctuations of a single mode of the incoherent source, thanks to the filtering function introduced by the local oscillator. Experimentally, a quadrature variance about three orders of magnitude larger than the vacuum noise is observed from an amplified spontaneous emission source, suggesting this scheme can tolerate much high technical noises in comparison with QRNGs based on measuring the vacuum noise. The high quality of this entropy source is evidenced by the small correlation coefficients of the acquired data.