Quantum channel locally interacting with environment

The quantum channel subject to local interaction with two-level environmentis studied. The two-level environment is regarded as a quantum bit (qubit) aswell as a pair of particles owned by Alice and Bob. The amount of entanglementinitially shared by Alice and Bob is distributed among these three qubits dueto the interaction. In this model, we show that the singlet fraction of thedecohered quantum channel is uniquely determined by the distributedentanglement. When the decohered quantum channel is used under the standardteleportation scheme, the optimal teleportation fidelity is well understood byconsidering the remaining entanglement between environment and transmittedstate.Comment: 4 pages, 2 figures, accepted to Phys. Rev. A, Brief Repor