Photon-subtracted squeezed thermal state: nonclassicality and decoherence

TL;DR

This paper explores the nonclassical properties of photon-subtracted squeezed thermal states, deriving analytical expressions for their quasi-probability distributions and analyzing how decoherence affects their negativity in phase space.

Contribution

It provides new analytical formulas for photon-subtracted squeezed thermal states and investigates their nonclassicality and decoherence effects in detail.

Findings

Wigner function negativity depends on thermal photon number and squeezing.

Photon subtraction introduces nonclassical features detectable via Wigner negativity.

Decoherence diminishes nonclassicality depending on environmental and state parameters.

Abstract

{\small We investigate nonclassical properties of the field states generated by subtracting any number photon from the squeezed thermal state (STS). It is found that the normalization factor of photon-subtracted STS (PSSTS) is a Legendre polynomial of squeezing parameter }${\small r}${\small \ and average photon number }$\bar{n}$ {\small of thermal state. Expressions of several quasi-probability distributions of PSSTS are derived analytically. Furthermore, the nonclassicality is discussed in terms of the negativity of Wigner function (WF). It is shown that the WF of single PSSTS always has negative values if }$\bar{n}<\sinh^{2}r${\small \ at the phase space center. The decoherence effect on PSSTS is then included by analytically deriving the time evolution of WF. The results show that the WF of single PSSTS has negative value if }$2\kappa t<\ln\{1-(2\bar{n}+1)(\bar{n}-\sinh^{2}% r)${\small }$[(2\mathfrak{N}+1)(\bar{n}\cosh2r+\sinh^{2}r)]\}${\small, which is dependent not only on average number }$\mathfrak{N}${\small \ of environment, but also on }$\bar{n}$ {\small and }$r${\small . }