Quantum Teleportation Without Loss Of Information

Quantum entanglement is one of the most important physical resources in quantum infor-mation science,and has played an important role in quantum information processing,such as quantum teleportation,super encoding,quantum key distribution and so on.So far,many impor-tant achievements have been obtained in the quantum teleportation.In this thesis,we propose a scheme for probabilistic teleportation of an arbitrary unknown two-qubit state without losing the information of the state to be teleported.The general thought is that Alice in the laboratory A transmits an arbitrary unknown two-qubit state(?)to Bob in the laboratory B through the four-particle partially entangled state(?).In the quantum teleportation process,we specify that particles 1,particle 2,particle 5,and particle 6 belong to Alice,particle 3 and particle 4 belong to Bob.Be-cause laboratory A and laboratory B are far away from each other,joint operations cannot be per-formed between them,only local unitary operations are performed.When Alice performs the joint measurements on the particles(particle 1,particle 2,particle 5,particle 6)of her own,and tells Bob the results of the measurement by the classic channel.According to the measurements results of the Alice,Bob carries out the appropriate local unitary operations on his own particles(particle 3,particle 4),and can obtain two-qubit state(?).If the quantum teleportation fails,the two-qubit state(?)remains intact in Alice's particles,and it can be transmitted over and over again,and until success.The diff-iculty of the scheme is that the local operations must be unitary operations,and to find these unitary operations is the key to realizing quantum teleportation without loss of information.The innovation of the scheme is tele-porting probabilistically an arbitrary unknown two-qubit state without losing the information,and the amount of information carring multiplied by several times than the information of one-qubit.The thesis is mainly composed of the following parts.In the first chapter,we introduce some basic concepts of the quantum information,such as quantum measurement,quantum entangle-ment and so on.In the second chapter,we give the related knowledge of the quantum teleportation and the probabilistic quantum teleportation.The third chapter is the core of this thesis,and is also our main works,which includes:Firstly,we propose a specific implementation scheme for probabilistic quantum teleportation of an arbitrary unknown two-qubit state without losing the information of the state to be teleported,and give the detailed implementation process.Secondly,in view of the physical feasibility of the quantum logic gate,we give the design scheme of the four-particle entanglement state as quantum channel using the quantum logic gate,and the quantum circuit.Thirdly,the complex multilevel unitary matrix is difficult to be realized in the physical ex-periment,for this reason,we decompose the complex multilevel unitary matrix into multiple two level unitary matrices.Lastly,we also propose a controlled probabilistic teleportation scheme of an arbitrary un-known one-qubit state without losing the information of the state to be teleported.The fourth chapter is the brief summary and outlook of the thesis.