# Impact of photon addition and subtraction on nonclassical and phase properties of a displaced Fock state

## TL;DR

This paper systematically investigates how photon addition and subtraction influence the nonclassical and phase properties of displaced Fock states, revealing that photon addition enhances nonclassicality and photon subtraction affects phase properties.

## Contribution

It provides a comprehensive analysis of photon addition/subtraction effects on displaced Fock states, highlighting their roles in enhancing nonclassicality and modifying phase properties.

## Key findings

- Photon addition generally improves nonclassicality.
- Photon subtraction induces squeezing and alters phase properties.
- Higher-order nonclassicality criteria detect nonclassicality beyond lower-order criteria.

## Abstract

Various nonclassical and quantum phase properties of photon added then subtracted displaced Fock state have been examined systematically and rigorously. Higher-order moments of the relevant bosonic operators are computed to test the nonclassicality of the state of interest, which reduces to various quantum states (having applications in quantum optics, metrology and information processing) in different limits ranging from the coherent (classical) state to the Fock (most nonclassical) states. The nonclassical features are discussed using Klyshko's, Vogel's, and Agarwal-Tara's criteria as well as the criteria of lower- and higher-order antibunching, sub-Poissonian photon statistics and squeezing. In addition, phase distribution function and quantum phase fluctuation have been studied. These properties are examined for various combinations of number of photon addition and/or subtraction and Fock parameter. The examination has revealed that photon addition generally improves nonclassicality, and this advantage enhances for the large (small) values of displacement parameter using photon subtraction (Fock parameter). The higher-order sub-Poissonian photon statistics is only observed for the odd orders. In general, higher-order nonclassicality criteria are found to detect nonclassicality even in the cases when corresponding lower-order criteria failed to do so. Photon subtraction is observed to induce squeezing, but only large number of photon addition can be used to probe squeezing for large values of displacement parameter. Further, photon subtraction is found to alter the phase properties more than photon addition, while Fock parameter has an opposite effect of the photon addition/subtraction. Finally, nonclassicality and non-Gaussianity is also established using $Q$ function.