# Manipulating nonclassicality via quantum state engineering processes: Vacuum filtration and single photon addition

## TL;DR

This paper compares vacuum filtration and single photon addition processes in quantum state engineering, analyzing their effects on nonclassicality in various quantum states using multiple witnesses and measures, revealing nuanced impacts on nonclassical features.

## Contribution

It provides a comparative analysis of two quantum state engineering processes and their influence on nonclassicality, using diverse criteria and quantifiers for the first time.

## Key findings

- Vacuum filtration and photon addition can enhance nonclassicality in quantum states.
- Not all nonclassical features are guaranteed by hole burning processes.
- Certain nonclassical properties like squeezing are not always observed after these processes.

## Abstract

The effect of two quantum state engineering processes that can be used to burn hole at vacuum in the photon number distribution of quantum states of radiation field are compared using various witnesses of lower- and higher-order nonclassicality as well as a measure of nonclassicality. Specifically, the witnesses of nonclassical properties due to the effect of vacuum state filtration and a single photon addition on an even coherent state, binomial state and Kerr state are investigated using the criteria of lower- and higher-order antibunching, squeezing and sub-Poissonian photon statistics. Further, the amount of nonclassicality present in these engineered quantum states is quantified and analyzed by using an entanglement potential based on linear entropy. It is observed that all the quantum states studied here are highly nonclassical, and on many occasions the hole burning processes are found to introduce/enhance nonclassical features. However, it is not true in general. The investigation has further revealed that despite the fact that a hole at vacuum implies a maximally nonclassical state (as far as Lee's nonclassical depth is used as the quantitative measure of nonclassicality). However, any particular process of hole burning at vacuum does not ensure the existence of a particular nonclassical feature. Specifically,lower- and higher-order squeezing are not observed for photon added even coherent state and vacuum filtered even coherent state.