Atomic quantum information processing in low-Q cavity in the intermediate coupling region

Abstract

We present an atomic-state entangler with single atoms trapped in separated low-Q cavities, a coherent optical pulse as a quantum channel, a photon detector that only distinguishes the vacuum and nonvacuum states, and basic optical elements based on the input–output process in the intermediate coupling region with a higher probability and fidelity. The atomic-state entangler is meaningful because it does not need a strong coupling cavity and a single-photon source and could be feasible for large-scale quantum computation and quantum communication in the future. Based on this entangler, quantum information nonlocal transfer without classical communication, the quantum controlled-NOT gate, the four-particle |χ〉 state, the N-particle Greenberger-Horne-Zeilinger (GHZ) state, and cluster-state generation can be realized completely, which is useful in large-scale and nonlocal quantum information processing.