Entanglement of coherent superposition of photon-subtraction squeezed vacuum

摘要

A new kind of non-Gaussian quantum state is introduced by applying nonlocal coherent superposition (tau alpha + sb)(m) of photon subtraction to two single-mode squeezed vacuum states, and the properties of entanglement are investigated according to the degree of entanglement and the average fidelity of quantum teleportation. The state can be seen as a single-variable Hermitian polynomial excited squeezed vacuum state, and its normalization factor is related to the Legendre polynomial. It is shown that, for tau = s, the maximum fidelity can be achieved, even over the classical limit (1/2), only for even-order operation m and equivalent squeezing parameters in a certain region. However, the maximum entanglement can be achieved for squeezing parameters with a pi phase difference. These indicate that the optimal realizations of fidelity and entanglement could be different from one another. In addition, the parameter tau/s has an obvious effect on entanglement and fidelity.