Quantum random number generators (QRNGs) based on quadrature measurements of the vacuum have so far used balanced homodyne detection to obtain a source of high entropy. Here we propose a simple direct detection measurement scheme using only a laser and a photodiode that still extracts randomness from vacuum fluctuations. We prove the security of the QRNG based on a reduced set of assumptions in comparison to previous security proofs for quadrature detection as our proof does not require the laser or electronic noise to be Gaussian. Using a low-cost setup based on a vertical-cavity surface-emitting laser we experimentally implement the QRNG scheme. We propose a system characterization method, apply it to our implementation and demonstrate a real-time randomness extraction rate of 3.41 Gbit per second. The unique combination of speed, low cost, and rigorous security proof gives our QRNG design a large potential for a wide-scale usage in a variety of applications ranging from quantum key distribution to mobile applications and internet of things.
@article{arxiv.2310.02354,
title = {Multi-Gbps quantum randomness source based on direct detection and vacuum states},
author = {Dino Solar Nikolic and Cosmo Lupo and Runjia Zhang and Tobias Rydberg and Ulrik L. Andersen and Tobias Gehring},
journal= {arXiv preprint arXiv:2310.02354},
year = {2023}
}