Non-classicality and decoherence of states generated via quantum excitation on Gaussian states in a thermal environment

Abstract

We investigate non-classical properties of states generated via quantum excitation on the squeezed coherent state (SCS). It was found that the normalisation factor is a summation form of Hermitian polynomial of squeezing parameter r and amplitude α of the coherent state. By taking advantage of the completeness relation of coherent states and the characteristic of the special function, the compact expression of quasiprobability distribution function was derived analytically. Furthermore, the non-classicality was discussed and compared by virtue of exploring especially the sub-Poissonian statistics and negative of the Wigner function (WF). The results show that photon addition operation may be a more effective method for the non-classicality enhancement than photon subtraction from the SCS under some conditions. Meanwhile, the negative volume of the WF as a function r exhibits remarkable oscillations as well with fixed smaller amplitude α for larger values of m. The fidelity of quantum teleportation is also analysed. It is shown that photon addition can obtain more higher fidelity than photon subtraction. Moreover, larger photon addition and subtraction numbers all may result in lower fidelity. In addition, the de-coherence effect on the photon-added SCS (PASCS) in the thermal environment is then included by analytically deriving the time evolution of WF, which manifests that the WFs finally become positive when the decay time exceeds a threshold value.