arXiv subjects

Tobias Rydberg

Publications and source records attributed to Tobias Rydberg.

2 recordsLinked to original sources

arXiv2023

Multi-Gbps quantum randomness source based on direct detection and vacuum states

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.

quant-ph↗

arXiv2020

Ultra-fast real-time quantum random number generator with correlated measurement outcomes and rigorous security certification

Quantum random number generators (QRNGs) promise perfectly unpredictable random numbers. However, the security certification of the random numbers in form of a stochastic model often introduces assumptions that are either hardly justified or indeed unnecessary. Two important examples are the restriction of an adversary to the classical regime as well as negligible correlations between consecutive measurement outcomes. Additionally, non-rigorous system characterization opens a security loophole. In this work we experimentally realize a QRNG that does not rely on the aforementioned assumptions and whose stochastic model is established by a rigorous -- metrological -- approach. Based on quadrature measurements of vacuum fluctuations, we demonstrate a real-time random number generation rate of 8 \,GBit/s. Our security certification approach offers a number of practical benefits and will therefore find widespread applications in quantum random number generators. In particular, our generated random numbers are well suited for today's conventional and quantum cryptographic solutions.

quant-ph↗