Multi-particle Quantum Teleportation

In 1993, Bennett et al first proposed a protocol for teleporting an unknown pure state based on dual usage of classical and quantum channels. From then on, more and more research groups focus their attention on the topic and dramatic progress has been made in both theory and experiment.Teleportation of an unknown quantum state include three processes. The fires is preparing entangled ERP states. The second is performing joint Bell state measurements on the particle that will be teleported and one particle of the ERP state. The third is performing a unitary thansformation on the second particle of the ERP state. This thesis investigates the basic theory of quantum teleportation and makes a review of traditional schemes for single qubit and multi-qubit teleportation. Through the non-locality of the quantum entanglement, teleportation schemes of arbitrary three-particle states are proposed. A scheme for teleportation of an arbitrary three-qubit state using generalized Bell measurement is proposed. 64 kinds of orthogonal generalized Bell states are constructed, serving as a similar position to the traditional four Bell states, to help complete faithful teleportation. With the aid of mutual classical communication and some relevant single qubit local operations, the receiver Bob successfully restores the original state with the total possibility one by utilizing a maximally entangled six-qubit state as quantum channel. Utilizing the general quantum teleportation protocol, in this scheme, a new method is presented by which multi-qubit quantum information can be teleported in a much easier way. It has been extended to teleportation of an arbitrary N-qubit state via entanglement swapping and probabilistic teleportation is investigated as well, which has a more general meaning. N non-maximally entangled triplet GHZ states (Greenberger--Horne--Zeilinger), taking the place of the previous EPR states (Einstein-- Podolsky-- Rosen), serve as quantum channels, which avoids introducing extra auxiliary qubit. In order to complete the teleportation, Alice has to devide all qubits into N parts and make Bell--State measurement on qubit pair (i, xi) and tell Bob the measurement result through classical channel, then Bob perform some simple local operations on qubits (yi , zi) to finish teleporting the i-th qubit.