Random Number Generation Utilizing Timing Jitters of Single-Flux-Quantum Propagation

We present superconducting hardware random number generators comprising single-flux-quantum (SFQ) digital circuits. We refer to them as SFQ oscillator-based hardware random number generators, or SO-HRNGs in short. The source of randomness in SO-HRNGs is timing jitters induced by thermal noises in integrated circuits. Test circuits were fabricated using a 10 kA/cm
²
Nb/AlOx/Nb integration process, and measured in a liquid helium bath. The NIST FIPS 140-2 test suite was used for evaluation of the randomness of generated random numbers. For a single-output SO-HRNG, pass rates of 100% were confirmed. For a triple-output SO- HRNG, on the other hand, pass rates for two outputs reached 100%, whereas those for the rest were not as high as 100%, 76% at the highest.