Qing Lin
Quantum Dicke state belongs to the class of maximally entangled state. Due to its complicated entangled structure and robustness against decoherence, it is the important resource for the investigation of entanglement properties and the creation of quantum network. How to generate Dicke state and apply Dicke state in quantum communication protocol becomes a hot topic in the area of quantum information science. In this paper, we focus on the problem how to create arbitrary multi-photon Dicke state efficiently. The experimental generations and applications of four-photon and six-photon Dicke state had been reported in recent years. However, the generation is not scalable, that is it is difficult to generate Dicke state with more photons only using spontaneous parametric down-conversion and linear optical technology. If assisted with the weak cross-Kerr nonlinearity, it is possible to generate multi-photon Dicke state with some probability. However, it is still impossible to generate Dicke state with arbitrary coefficients, and the success probability decreases exponentially with the increasing of photon number. Here, we use three element gates called c-path gate, merging gate, entangler, which are introduced in former works, to design the generation of Dicke state. Firstly, the deterministic scheme of four-photon Dicke state generation is provided. After that, we modify the former W state generation scheme to be available for arbitrary coefficients W state generation. For the generation of arbitrary Dicke state, we decompose it to be a series of W state generations, with the help of c-path gates and merging gates. This scheme is deterministic and available for arbitrary coefficients. Especially, for some classes of Dicke states generation, the required resources are only polynomial growth with the increasing of photon number. All these features will make the investigation of multi-photon Dickes to be more convenient than the former schemes. In addition, our scheme is theoretically feasible with the current experimental technology.
Zhongguo kexue. Wulixue Lixue Tianwenxue•Apr 1, 2014•1 citation