Design Of Quantum Teleportation And Remote State Preparation Protocol

With the rapid development of emerging industry such as e-commerce, mobile payment, internet information security has been becoming a high-profile issue in the world.Because quantum communication has the characteristic of unconditional security and high efficiency in theory, it has a great application value and prospect in the information security and will be coming into people’s daily life. In this thesis, we mainly study the related protocols of quantum teleportation and remote state preparation. Using linear algebra as a tool, we design three quantum communication protocols based on different entangled states and quantum measurement methods. The main results are as follows:1. Quantum teleportation. A scheme for bidirectional controlled teleportation of Bell-type State is proposed by using non-maximally entangled state as quantum channel. Based on projective measurement, positive-operation valued measurement, control-not operation and appropriate unitary operations, two users can simultaneously transmit states to each other under the control of the supervisor, and it cannot be successful without permission of the controller.The success probability of teleportation can reach 100% if and only if the entangled state is maximally entangled.2. Remote state preparation. Using a seven-qubit entangled state as the quantum channel,we put forward a protocol for implementing five-party bidirectional controlled joint remote state preparation. In the scheme, the senders Alice and Charlie want to remotely prepare a single-qubit state at Bob’s site, and the senders Bob and David wish to prepare the other single-qubit state at Alice’s site under the control of the supervisor Fred. The success probability of teleportation can reach 100% if and only if the participants Charlie, David and Fred cooperate with each other. Only local operation and classical communication will be used, so the scheme with five-party is easily realized in physical experiment.3. Remote state preparation for star network. Maximally entangled state will degenerate into partially entangled state by the influence of external factors, so we put forward a probabilistic remote state preparation scheme. Two distant user nodes do not initially share entanglement with each other. The required entanglement among user nodes is established through entanglement swapping. Finally, with the help of Bell-basis measurement, auxiliary qubits and appropriate unitary transformation and single-qubit measurement, one-way and bidirectional preparations of arbitrary single-qubit state can be successfully realized with a certain probability.