Experimental realisation of generalised qubit measurements based on quantum walks

TL;DR

This paper demonstrates an experimental method to perform generalized qubit measurements using a quantum walk setup with single photons, enabling implementation of various POVMs including trine, SIC, and unambiguous state discrimination.

Contribution

It presents the first experimental realization of generalised qubit measurements based on quantum walks with a novel optical setup.

Findings

Successfully implemented Trine-POVM, SIC-POVM, and unambiguous state discrimination.

Demonstrated control over measurement types using quantum walk architecture.

Validated the feasibility of quantum walk-based measurement schemes for quantum information processing.

Abstract

We report an experimental implementation of a single-qubit generalised measurement scenario(POVM) based on a quantum walk model. The qubit is encoded in a single-photon polarisation. The photon performs a quantum walk on an array of optical elements, where the polarisation-dependent translation is performed via birefringent beam displacers and a change of the polarisation is implemented with the help of wave-plates. We implement: (i) Trine-POVM, i.e., the POVM elements uniformly distributed on an equatorial plane of the Bloch sphere; (ii) Symmetric-Informationally- Complete (SIC) POVM; and (iii) Unambiguous Discrimination of two non-orthogonal qubit states.