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 for GHZ state generation through noisy channel. Numbers 1–11 denote the polarization beam splitters (PBS), whose function is to translate R polarization light and reflect L polarization light. The role of the half wave plate 1 (HWP1)–HWP4 is to perform σ x operation (| R ⟩↔| L ⟩) on photon state, while the function of HWP5 and HWP6 can be represented as . The photon flying time difference between length L 0 and L 1 ( L 1> L 0) is big enough to make the optical switch transmit or reflect. Nevertheless, this time difference should be taken to be much less than the photon fluctuation time L/c in the noisy channel to ensure that the noise has the same effect on the photon coming from path L 0 or L 1. The action of L D, which has a similar length to L 1, is to delay the photon pulse in the lower path. The lengths of paths without labelling L 0, L 1, L , and L D are much less than L 1– L 0 and can be ignored.