Research About Quantum Teleportation In Thermally Entangled Channels

This thesis investigates the basis theory of teleportation in pure channels firstly, then the teleportation in thermally entangled channels is also analyzed. In this paper, we mainly study quantum entanglement in Heisenberg XX model, with that, the quantum teleportation via Heisenberg thermally entangled state is studied. At the same time, entanglement teleportation, using thermally entangled state of two two-qubit Heisenberg XX chain as resource, with nonzero thermal entanglement and fidelity better than any classical communication protocol is possible. And then, the influence about entanglement and teleportation due to the effects of environment (temperature T and magnetic field B), is analyzed respectively, we figure out the critical temperature when the concurrence is zero and the fidelity is 2/3. It is found that, in Heisenberg thermally entangled channels, we will get different result with different weight term of each channel, we analyze the course with the largest weight term.As the whole, it is found that, in Heisenberg XX model, the condition for the thermally quantum channel to teleport states with fidelity strictly greater than 2/3 is expectedly stronger than that for thermal concurrence to be nonzero. In addition, the critical temperature is independent on the magnetic field B when the concurrence is zero, and the critical temperature is dependent on the magnetic field B when the fidelity is 2/3. It is also found that with increasing magnetic field B we have an increasing range of nonzero thermal entanglement which is, however, not suitable for quantum teleportation. Therefore, the thermal concurrence only describes certain aspects of the thermal entanglement. In particular, it does not indicate the quality of thermal entanglement for quantum...