Optimal randomness certification from one entangled bit

TL;DR

This paper demonstrates that using general measurements on a two-qubit entangled state can certify up to two bits of randomness, doubling the amount achievable with projective measurements, thus optimizing device-independent randomness certification.

Contribution

It introduces the use of positive-operator-valued measures for maximal randomness certification from a single entangled bit, surpassing previous projective measurement limits.

Findings

General measurements certify up to two bits of randomness

Optimal randomness certification from a single entangled bit

Advantage of POVMs over projective measurements

Abstract

By performing local projective measurements on a two-qubit entangled state one can certify in a device-independent way up to one bit of randomness. We show here that general measurements, defined by positive-operator-valued measures, can certify up to two bits of randomness, which is the optimal amount of randomness that can be certified from an entangled bit. General measurements thus provide an advantage over projective ones for device-independent randomness certification.