Local environment can enhance fidelity of quantum teleportation - art. no.012311

We show how an interaction with the environment can enhance fidelity of qua ntum teleportation. To this end, we present examples of states which cannot be made useful for teleportation by any local unitary transformations; nev ertheless, after being subjected to a dissipative interaction with the loca l environment, the states allow for teleportation with genuinely quantum fi delity. The surprising fact here is that the necessary interaction does not require any intelligent action from the parties sharing the states. In pas sing, we produce some general results regarding optimization of teleportati on fidelity by local action. We show that bistochastic processes cannot imp rove fidelity of two-qubit states. We also show that in order to have their fidelity improvable by a local process, the bipartite states must violate the so-called reduction criterion of separability.