Minimal scheme for certifying three-outcome qubit measurements in the prepare-and-measure scenario

TL;DR

This paper presents a minimal, experimentally feasible scheme for certifying three-outcome qubit measurements in a prepare-and-measure setting, advancing semi-device-independent quantum measurement certification methods.

Contribution

It introduces the first minimal certification scheme requiring only three state preparations and two measurements for three-outcome qubit measurements, with practical experimental examples.

Findings

Minimal scheme uses three preparations and two measurements.

Experimental feasibility demonstrated with practical examples.

Discussion on dimension assumptions and their mitigation.

Abstract

The number of outcomes is a defining property of a quantum measurement, in particular, if the measurement cannot be decomposed into simpler measurements with fewer outcomes. Importantly, the number of outcomes of a quantum measurement can be irreducibly higher than the dimension of the system. The certification of this property is possible in a semi-device-independent way either based on a Bell-like scenario or by utilizing the simpler prepare-and-measure scenario. Here we show that in the latter scenario the minimal scheme for a certifying an irreducible three-outcome qubit measurement requires three state preparations and only two measurements and we provide experimentally feasible examples for this minimal certification scheme. We also discuss the dimension assumption characteristic to the semi-device-independent approach and to which extend it can be mitigated.