High-speed quantum random number generation for secure data communications

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Random numbers are essential for creating the cryptographic keys that ensure our personal information is secure online. Generating truly random numbers in software alone is impossible, since computers use a completely predictable algorithm for this purpose. Only hardware random number generators can produce true random numbers, and even these are limited by aging effects in classical noise sources. To be truly random one needs a quantum random number generator (RNG), and such devices will be integral to the future of cryptography, forming the basis of secure communications and data processing. Due to their respective technological approaches the clock speeds of commercially available quantum RNGs are limited to few-hundred Mbit/s data streams, a bottleneck that is incompatible with future telecommunications demands. In this IUK project, which is collaborative with commercial partner Chromacity Ltd., we will demonstrate a route to 100s-of-Gb/s quantum RNG based on novel laser technology. Using a unique high -power green femtosecond laser developed by Chromacity, Heriot-Watt will investigate how amplified parametric downconversion can be used to obtain randomly phased pulse pairs. Vacuum fluctations seed the phases of the downconverted pulses, following which a heterodyne phase comparison yields a random bit stream detectable on a classical fast photodiode. Excitingly, our proposed approach is highly scalable, giving the potential to massively outperform current approaches and enabling the system to keep pace with the demand for high-bit-rate random numbers continues to increase.