Nonclassical properties of photon-added two-mode squeezed thermal states and their decoherence in the thermal channel

作者:Meng, Xiang-guo*; Wang, Zhen; Fan, Hong-yi; Wang, Ji-suo; Yang, Zhen-shan
来源:Journal of the Optical Society of America B-Optical Physics, 2012, 29(7): 1844-1853.
DOI:10.1364/JOSAB.29.001844

摘要

We investigate nonclassicality and decoherence of field states generated with the non-Gaussian operation of photon addition to a two-mode squeezed thermal state (TSTS) using the normally ordered density operator of the photon-added TSTS (PTSTS). The normalization factor of the PTSTS is just a Jacobi polynomial of the squeezing parameter gamma and the average photon number (n) over bar of the thermal field. We show that the fields in such states exhibit remarkable quantum features, such as sub-Poissonian photon statistics, the anti-bunching effect, and photon-number distribution. The nonclassicality is discussed in phase space based on the partial negativity of the Wigner WF) with two-variable Hermite polynomials. The results show that the non-Gaussian WF always exhibits the quantum interference structure caused by the two-mode squeezing operation and has some negative regions for any value of (n) over bar, gamma, and the photon-addition numbers m, n. In addition, the effect of decoherence on the PTSTS in the thermal channel is studied by analytically deriving the time-evolution WF. We find that the WF becomes Gaussian (corresponding to a classical thermal state) at long times, losing its nonclassicality as a result of decoherence, and a larger m (or n) leads to a longer decoherence time kappa t.