We study an entangled two-mode coherent state within the framework of
2×2-dimensional Hilbert space. We investigate the problem of quantum teleportation of
a superposition coherent state via an entangled coherent channel. By three different
measures with the titles ``minimum assured fidelity (MASF)”, ``average teleportation
fidelity” and ``optimal fidelity (f)” we study the quality of this kind of teleportation.
Decoherence properties of the entangled coherent state due to channel losses are
analysed. For a symmetric noise channel, the degradation of optimal fidelity and degree
of entanglement are calculated. Also by two different measures with the titles
``concurrence” and ``entanglement of formation” we study the amount of entanglement
of a decohered quantum channel and discuss its details. We demonstrate that
entanglement of the decohered entangled coherent state is reduced but not throughly
lost. Finally we find that the optimal fidelity of the decohered entangled coherent state is
more than the classical limit and the decohered entangled coherent state may be useful
for quantum teleportation. Manuscript profile