Non-classicality indicators for entangled and squeezed number states

TL;DR

This paper compares two non-classicality indicators, Kenfack's and Sadeghi's, for entangled and squeezed number states, demonstrating Sadeghi's indicator's advantages and its relation to entropy.

Contribution

It introduces a comparative analysis of non-classicality indicators for various quantum states, highlighting Sadeghi's indicator's effectiveness and its connection to entropy.

Findings

Sadeghi's indicator is more beneficial for two-level entangled states.

A correspondence exists between Sadeghi's indicator and Von Neumann entropy.

Sadeghi's indicator is sensitive to squeezing parameters in superpositions.

Abstract

Many non-classicality indicators are used to measure quantum effects of different systems. Kenfack's and Sadeghi's non-classicality indicators are introduced in terms of the amount of Wigner function's negativities and interferences in phase space quantum mechanics, respectively. They are, effectively, applied for some real distribution functions. In this paper, we compared these non-classicality indicators for the entangled state of photonic number states in the Wigner, Husimi and Rivier representations. It is shown that for a two-level entangled state, Sadeghi's indicator has more benefits with respect to the Kenfack's indicator. For the two-level entangled state, we show a correspondence between the Sadeghi's non-classicality indicator and the Von Neumann entropy. It is also shown that for the superposition of squeezed number state the Sadeghi's (and no Kenfack's) non-classicality indicators is sensible with respect to the squeezing parameter for a superposition of squeezed number states.