Travis S. Humble

Achieving computational advantage using NISQ devices on practically useful problems is a long standing challenge. We report two papers that experimentally demonstrate a concrete application, namely certified randomness generation, which could be useful for multi-party cryptographic protocols and improving imperfect physical sources of randomness. Both papers involve substantial theoretical contributions to the protocol. We devise a realistic protocol that maximizes practical hardness. The verifier first asks the server to prepare a quantum state using a random circuit and then sends a random measurement basis right before the result must be received. This is repeated for many rounds. We show complexity theoretic evidence for entropy generation and provide improved entropy bounds against adversaries with oracle access to the random circuits. We also construct an end-to-end application of randomness amplification of imperfect sources into nearly perfect randomness, notably achieving everlasting security which uplifts computational security to information theoretic security.

We present the algorithmic design of a quantum random number generator (QRNG), the subsequent synthesis of a physical design and its verification using quantum statistical testing. We apply this concept in a new implementation of a QRNG that consists of tapered amplifier optical semiconductor devices and an array of random number registration techniques, including quantum feedback/forward control for removing bias. We also describe how quantum statistical testing can be used to diagnose channel noise in QKD protocols.