Quantum vs. noncontextual semi-device-independent randomness certification

TL;DR

This paper compares quantum and classical physics in randomness certification using semi-device-independent protocols, revealing a quantum advantage in certifying more randomness when states are not unambiguously identified.

Contribution

It develops semi-device-independent protocols based on maximum-confidence discrimination, demonstrating a quantum advantage over noncontextual classical models in randomness certification.

Findings

Quantum devices certify more randomness than noncontextual models.

Quantum advantage exists when input states are not unambiguously identified.

Protocols generalize unambiguous and minimum-error state discrimination.

Abstract

We compare the power of quantum and classical physics in terms of randomness certification from devices which are only partially characterised. We study randomness certification based on state discrimination and take noncontextuality as the notion of classicality. A contextual advantage was recently shown to exist for state discrimination. Here, we develop quantum and noncontextual semi-device independent protocols for random-number generation based on maximum-confidence discrimination, which generalises unambiguous and minimum-error state discrimination. We show that, for quantum eavesdropppers, quantum devices can certify more randomness than noncontextual ones whenever none of the input states are unambiguously identified. That is, a quantum-over-classicaladvantage exists.