Time-bin-encoding-based remote states generation of nitrogen-vacancy centers through noisy channels*
Su Shi-Leia), Chen Lib), Guo Qia), Wang Hong-Fuc), Zhu Ai-Dongc), Zhang Shoua),c)†
       
A schematic diagram to generalize GHZ state generation to n -qubit case among n nodes. The role of HWP1-HWP4 n −4 is to perform a σ x operation on the photon pulse, while the role of HWP4 n −3 and HWP4 n −2 is to realize the transformation . The control sequences of optical switches are shown in Fig. 7 . Subscript k denotes the sequence number of the node where the optical switches are located. It should be noted that the optical path and the elements from node 2 to node n − 1 are all same, except the the delay lines (marked with green boxes) under the optical switches S 9 k −9, whose length is designed as L D j = 2 j −1 L D(1 ⩽ j ⩽ n −1).