Kenfack Zyczkowski indicator of nonclassicality for two non-equivalent representations of Wigner function of qutrit

TL;DR

This paper investigates the Kenfack-Zyczkowski nonclassicality indicator for qutrits, analyzing how different Wigner function representations affect the measure of nonclassicality in finite-dimensional quantum systems.

Contribution

It introduces an analysis of the nonclassicality indicator across non-equivalent Wigner function representations for qutrits, highlighting the sensitivity of the measure to the choice of kernel.

Findings

Computed the indicator for various Wigner function representations of a qutrit.

Showed the indicator's dependence on the choice of Stratonovich-Weyl kernel.

Provided explicit parameterization of the Wigner function moduli space for qutrits.

Abstract

The Wigner function of a finite-dimensional system can be constructed via dual pairing of a density matrix with the Stratonovich-Weyl kernel. Following Kenfack and $\dot{\text{Z}}$yczkowski, we consider the indicator of nonclassicality of a finite-dimensional quantum system which depends on the volume of the negative part of the Wigner function. This indicator is defined over the unitary non-equivalent classes of quantum states, i.e. represents an invariant, but since for a given quantum system there is no unique Wigner function it turns to be sensitive to the choice of representations for the Wigner function. Based on the explicit parameterization of the moduli space of the Wigner functions, we compute the corresponding Kenfack-$\dot{\text{Z}}$yczkowski indicators of a 3-level system for degenerate, unitary non-equivalent Stratonovich-Weyl kernels.