Entanglement of one- and two-mode combination squeezed thermal states and its application in quantum teleportation

In view of the fact that one- and two-mode combination squeezed vacuum states may exhibit stronger squeezing in a certain range, we introduce one- and two-mode combination squeezed thermal states (OTCSTS) and investigate the property of entanglement in detail. Using the remarkable property of Weyl ordering, i.e., the order-invariance of Weyl ordered operator under similar transformations, we conveniently derive the analytical expression of entanglement degree-logarithmic negativity, and then present the condition of keeping entanglement for these squeezed thermal states. It is found that the OTCSTS possesses higher entanglement than the usual two-mode squeezed thermal states for any non-zero squeezing parameter. As an application, the quantum teleportation for coherent state is considered by using the OTCSTS as an entangled channel. It is shown that the teleportation fidelity can only be enhanced within a certain range of parameters, which is just the same as the condition of exhibiting stronger squeezing in one quadrature. In addition, the condition of realizing effective quantum teleportation (> 1/2) is obtained analytically.