ar X iv : q ua nt - p h / 99 10 02 1 v 1 6 O ct 1 99 9 Probabilistic Teleportation and Entanglement Matching

Teleportation may be taken as sending and extracting quantum information through quantum channels. In this report, it is shown that to get the maximal probability of exact teleportation through partially entangled quantum channels, the sender (Alice) need only to operate a measurement which satisfy an “entanglement matching” to this channel. An optimal strategy is also provided for the receiver (Bob) to extract the quantum information by adopting general evolutions. PACS Number(s) 03.67∗, 03.65.Bz Quantum teleportation, the process that transmits an unknown qubit from a sender (Alice) to a receiver (Bob) via a quantum channel with the help of some classical information, is originally concerned by Bennett, Brassard, Crepeau, Jozsa, Peres, and Wootters (BBCJPW) [1]. In their scheme, such a quantum channel is represented by a maximally entangled pair (any of the Bell states) and the original state could be deterministically transmitted to Bob. The process of teleportation may be regarded as sending and extracting quantum information via the quantum channel. We will apply this picture to investigate a partially entangled quantum channel. Because a mixed state can be purified to a Bell state with no probability [2− 4], a quantum channel of mixed state could never provide an teleportation with fidelity 1. Therefore only pure entangled pairs should be considered if we prefer an exact teleportation (even with some probability). For the reason of Schmidt disposition [5], a partially entangled pair may be expressed as