Theoretical Studies Of Generation Scheme And Application Of W State

The quantum informatics is an interdisciplinarity of quantum mechanics andinformation science, which developed rapidly recent years. Entanglement plays afundamental role in quantum information, so the quantum information can realizemany different functions, which are impossible in classical information, such asquantum dense coding, quantum key distribution, quantum teleportation, and quantumcomputing. In multiparitcle entanglement, W entanglement state has a unique propertythat is a more robust entanglement comparing with the other multiparitcleentanglement. So it makes sense to research W states.This paper mainly discussed the preparation and application of W states. Thesummary and analysis on W entanglement state are given. This paper includes thefollowing aspects:(1) Introducing the overseas and domestic research status about quantum entangle-ment. The definition of quantum entanglement and several common quantum entangl-ements are given. Finally, the problem of measuring entanglement and application ofquantum entanglement in quantum information are discussed.(2) Proposing and deriving a scheme for preparation of three-atom W state andthree-cavity W state via detuning interaction and resonant interaction in the cavityQED, and further introducing several schemes of preparation entangled states: ion trapscheme, superconducting quantum interference devices. Characteristics and advantagesand disadvantages of each scheme are also analysed.(3) Putting forward three schemes for generation of W states. Three identicalthree-level atoms interact with a single-mode cavity in the cavity QED; Two-photon W state with maximized fidelities, which can be generated by resonant interactionbetween three identical three-level atoms and four cavities via two-photon process;Generation of the multi-atom W state via detuning interaction of V-type three-levelatoms and two-mode cavity-field.(4) Two schemes for teleporting an unknown tripartite W state and GHZ statefrom a sender to either of the two receivers are proposed, where the quantum channelis composed of one or more three-particle W states. The results show that there is still acertain probability of successful teleportation. These schemes may be directlygeneralized to teleport n-particle entangled states.