Practical Semi-Device Independent Randomness Generation Based on Quantum State’s Indistinguishability

H. Tebyanian1, M. Zahidy1, M. Avesani1, A. Stanco1, P. Villoresi1, and G. Vallone1
Quantum Sci. Technol. 6, 045026 (2021)

1Department of Information Engineering, University of Padova, via Gradenigo 6/B, 35131 Padova, Italy

Semi-device independent (Semi-DI) quantum random number generators (QRNG) gained attention for security applications, offering an excellent trade-off between security and generation rate. This paper presents a proof-of-principle time-bin encoding semi-DI QRNG experiments based on a prepare-and-measure scheme. The protocol requires two simple assumptions and a measurable condition: an upper-bound on the prepared pulses’ energy. We lower-bound the conditional min-entropy from the energy-bound and the input-output correlation, determining the amount of genuine randomness that can be certified. Moreover, we present a generalized optimization problem for bounding the min-entropy in the case of multiple-input and outcomes in the form of a semidefinite program (SDP). The protocol is tested with a simple experimental setup, capable of realizing two configurations for the ternary time-bin encoding scheme. The experimental setup is easy-to-implement and comprises commercially available off-the-shelf (COTS) components at the telecom wavelength, granting a secure and certifiable entropy source. The combination of ease-of-implementation, scalability, high-security level, and output-entropy make our system a promising candidate for commercial QRNGs.