Figure 2
From: Hyper-parallel photonic quantum computation with coupled quantum dots
Schematic diagram for a spatial-CNOT gate operating on the spatial-mode DOF of a two-photon system.
Xi (i = 1, 2) represents a half-wave plate which is used to perform a polarization bit-flip operation X = |R〉〈L| + |L〉〈R| on the photon passing through it. CPBS represents a polarizing beam splitter in the circular basis, which transmits the photon in the polarization |R〉 and reflects the photon in the polarization |L〉, respectively. Zi (i = 1, 2) represents a half-wave plate which is used to perform a polarization phase-flip operation Z = −|R〉〈R| + |L〉〈L| on a photon.
