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

TL;DR

This paper introduces a fast, secure, and low-cost quantum random number generator using direct detection of vacuum states, achieving over 3 Gbps in real-time, suitable for widespread practical applications.

Contribution

It presents a novel direct detection scheme for QRNGs that simplifies implementation, reduces assumptions for security, and demonstrates high-speed randomness generation.

Findings

Achieved a real-time randomness extraction rate of 3.41 Gbit/sec.

Proposed a low-cost, practical QRNG setup using a VCSEL laser.

Provided a security proof that requires fewer assumptions than previous methods.

Abstract

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.