Generation Of Cluster States And Quantum Teleportation Via Cavity QED

Quantum entanglement is the most fundamental resource of quantum information science and plays a very key role in quantum teleportation, quantum dense coding, quantum algorithms and quantum computation. Specially, a particular class of entangled states, the cluster states have been shown to constitute a universal resource for so-called one-way quantum computation with assistant by one-qubit measurement only. So, it is important to make some research on cluster states. Meanwhile, quantum teleportation is one of the most striking fields in quantum communication, and also a interesting application of quantum entanglement. In this paper, we mainly discuss the generation of cluster states and the scheme for realizing teleportation a bipartite entangled coherent state via cavity quantum electrodynamics (QED).1. Generation of cluster statesWe propose two schemes for the generation of cluster states (include one-dimensional and two-dimensional) in the context of cavity QED. First and foremost, in the first scheme we prepare multi-cavity cluster states with information encoded in the coherent states which can reduce the apontaneous emission errors and the second scheme is to generate multi-atom cluster states, where qubits are represented by the states of cascade Rydberg atoms. Besides, both schemes are based on the atom-cavity interaction and the atomic spontaneous radiation can be efficiently reduced since the cavity frequency is largely detuned from the atomic transition frequency. Last but not least, by using the interlinkage of cluster states, it is very convenient to generate two-dimensional cluster states through two one-dimensional cluster states.2. Teleportation of a bipartite entangled coherent state via cavity QEDWe present a scheme for the teleportation of a bipartite entangled coherent state. Based on the atom-cavity-field interaction, the quantum channel is prepared and the scheme can be realized with high fidelity. For the coherent states |α> and |—α> are not orthogonal, the local transformations which are did by Bob to get the original states are not always unitary. In our proposal, we propose the local transformations for four different cases detailedly, especially when the local transformations are not unitary. The fidelity of the ECS is calculated and analyzed at length, and the result shows that the entanglement can be fulfilled with fidelity nearly 100% as long as |α| is not too small.