Enhancing quantum entropy in vacuum-based quantum random number generator

TL;DR

This paper investigates methods to enhance quantum entropy in vacuum-based quantum random number generators, demonstrating that increasing local oscillator intensity improves randomness extraction even under high classical noise conditions.

Contribution

It introduces a novel approach of boosting local oscillator power to enhance quantum entropy, outperforming traditional gain adjustments in noisy environments.

Findings

Achieved an 85.3% true randomness extraction ratio.

Demonstrated robustness of quantum entropy enhancement against classical noise.

Validated the method through experimental results.

Abstract

Information-theoretically provable unique true random numbers, which cannot be correlated or controlled by an attacker, can be generated based on quantum measurement of vacuum state and universal-hashing randomness extraction. Quantum entropy in the measurements decides the quality and security of the random number generator. At the same time, it directly determine the extraction ratio of true randomness from the raw data, in other words, it affects quantum random numbers generating rate obviously. In this work, considering the effects of classical noise, the best way to enhance quantum entropy in the vacuum-based quantum random number generator is explored in the optimum dynamical analog-digital converter (ADC) range scenario. The influence of classical noise excursion, which may be intrinsic to a system or deliberately induced by an eavesdropper, on the quantum entropy is derived. We propose enhancing local oscillator intensity rather than electrical gain for noise-independent amplification of quadrature fluctuation of vacuum state. Abundant quantum entropy is extractable from the raw data even when classical noise excursion is large. Experimentally, an extraction ratio of true randomness of 85.3% is achieved by finite enhancement of the local oscillator power when classical noise excursions of the raw data is obvious.