Quantum channel locally interacting with environment - art. no. 034301

The quantum channel subject to local interaction with two-level environment is studied. The two-level environment is regarded as a quantum bit (qubit) as well as a pair of particles owned by Alice and Bob. The amount of entan glement initially shared by Alice and Bob is distributed among these three qubits due to the interaction. In this model, we show that the singlet frac tion of the decohered quantum channel is uniquely determined by the distrib uted entanglement. When the decohered quantum channel is used under the sta ndard teleportation scheme, the optimal teleportation fidelity is well unde rstood by considering the remaining entanglement between environment and tr ansmitted state.