Entropy certification of a realistic QRNG based on single-particle entanglement

TL;DR

This paper demonstrates how to certify entropy in a realistic single-photon entangled quantum random number generator by analyzing device imperfections and memory effects, ensuring secure randomness generation.

Contribution

It introduces a semi-device independent method for entropy certification in SPE-based QRNGs considering realistic device non-idealities and detector memory effects.

Findings

Quantum randomness can be certified despite device imperfections.

Memory effects like dead time and dark counts are modeled and mitigated.

A new unbiased estimator for quantum transition probabilities is proposed.

Abstract

In single-particle entanglement (SPE) two degrees of freedom of a single particle are entangled. SPE is a resource that can be exploited both in quantum communication protocols and in experimental tests of noncontextuality based on the Kochen-Specker theorem. SPE can be certified via a test of quantum contextuality based on Bell inequalities. Experiments of Bell-like inequality violation by single particle entangled systems may be affected by an analogue of the locality loophole in this context, due to the presence of unavoidable non-idealities in the experimental devices which actually produce unwanted correlations between the two observables that are simultaneously measured. This issue is tackled here by quantitatively analyzing the behaviour of realistic devices in SPE experiments with photons. In particular, we show how it is possible to provide a semi-device independent randomness certification of realistic quantum random number generators based on Bell inequality violation by SPE states of photons. The analysis is further enlarged to encompass, with a Markovian model, memory effects due to dead time, dark counts and afterpulsing affecting single photon detectors, in particular when not dealing with coincidence measurements. An unbiased estimator is also proposed for quantum transition probabilities out of the collection of experimental data.