Quantum formalism on the plane: POVM-Toeplitz quantization, Naimark theorem and linear polarisation of the light

TL;DR

This paper explores POVMs on the Euclidean plane as quantum observables and quantizers, discusses their compatibility, provides a Naimark dilation, relates to Toeplitz quantization, and applies these concepts to light polarization and Stokes parameters.

Contribution

It introduces a detailed analysis of POVMs on the plane, linking them to Toeplitz quantization and providing conditions for the compatibility of fuzzy observables.

Findings

Naimark dilation for quantum operators associated with POVMs.

Relation established between POVMs and Toeplitz quantization.

Derived conditions for the compatibility of fuzzy observables.

Abstract

We investigate two aspects of the elementary example of POVMs on the Euclidean plane, namely their status as quantum observables and their role as quantizers in the integral quantization procedure. The compatibility of POVMs in the ensuing quantum formalism is discussed, and a Naimark dilation is found for the quantum operators. The relation with Toeplitz quantization is explained. A physical situation is discussed, where we describe the linear polarization of the light with the use of Stokes parameters. In particular, the case of sequential measurements in a real bidimensional Hilbert space is addressed. An interpretation of the Stokes parameters in the framework of unsharp or fuzzy observables is given. Finally, a necessary condition for the compatibility of two dichotomic fuzzy observables which provides a condition for the approximate joint measurement of two incompatible sharp observables is found.