Quantum information processing in decoherence-free subspace with nitrogen-vacancy centers coupled to a whispering-gallery mode microresonator

We investigate the input-output process with nitrogen-vacancy (NV) centers fixed on the surface of microtoroidal resonators (MTRs) with quantized whispering-gallery modes (WGMs). We demonstrate a photon-NV hybrid controlled phase flip (CPF) gate in decoherence-free subspace (DFS) with the inputoutput process. Efficient schemes of entanglement generation and quantum state transfer (QST) in DES are proposed. Our schemes removed the requirements of high-Q and strongly coupling for the physical systems, and DES encoding makes our schemes immune to collective dephasing. The experimental feasibility and challenge are discussed by considering the current experimental technology. (c) 2013 Elsevier B.V. All rights reserved