A Simple Method of Evaluating Laser Diode Suitability for Phase-Noise Based QRNG

TL;DR

This paper introduces a practical test scheme for evaluating semiconductor laser suitability in phase-noise based quantum random number generators, aiding system monitoring and device selection for security-critical applications.

Contribution

It presents a simple, accessible method to assess laser diode performance for QRNGs, including quality measures and acceptance criteria for security standards.

Findings

Effective measurement data demonstrating the method's reliability

Guidelines for setting acceptance boundaries based on quality measures

A reproducible procedure for QRNG system qualification

Abstract

Quantum random number generators (QRNGs) based on semiconductor laser phase noise are an inexpensive and efficient resource for true random numbers. Commercially available technology allows for designing QRNG setups tailored to specific use cases. However, it is important to constantly monitor whether the QRNG is performing according to the desired security standards in terms of independence and uniform distribution of the generated numbers. This is especially important in cryptographic applications. This paper presents a test scheme that helps to assess the acceptable operating conditions of a semiconductor laser for QRNG operation, using commonly accessible methods. This can be used for system monitoring, but crucially also to help the user choose the laser diode which better suits their needs. Two specific quality measurements, ensuring proper operation of the device, are explained and discussed. Setup-specific approaches for setting an acceptance boundary for these measures are presented and exemplary measurement data showing their effectiveness is given. By following the comprehensible procedure described here, a QRNG qualification environment tailored to specific security requirements can be reproduced.