Unconditional preparation of multipartite continuous-variable entangled states among remote parties

We demonstrate that the n-partite continuous-variable entanglement can be unconditionally prepared among n parties that share no common past,from n two-mode squeezed states.Both GHZ-like and cluster-like states can be generated for any nonzero squeezing in the entangled sources.An application of the resulting multipartite entangled state to a teleportation network is illustrated.     

Quantum walk under coherence non-generating channels

We investigate the probability distribution of the quantum walk under coherence non-generating channels. We definea model called generalized classical walk with memory. Under certain conditions, generalized classical random walk withmemory can degrade into classical random walk and classical random walk with memory. Based on its various spreadingspeed, the model may be a useful tool for building algorithms. Furthermore, the model may be useful for measuring thequantumness of quantum walk. The probability distributions of quantum walks are generalized classical random walkswith memory under a class of coherence non-generating channels. Therefore, we can simulate classical random walkand classical random walk with memory by coherence non-generating channels. Also, we find that for another class ofcoherence non-generating channels, the probability distributions are influenced by the coherence in the initial state of thecoin. Nevertheless, the influence degrades as the number of steps increases. Our results could be helpful to explore therelationship between coherence and quantum walk.