Alternative scheme for implementation of 3 qubit Fredkin gate with photonic bandgap crystal.

• All optical 3-qubit Fredkin gate with Photonic Band gap Crystal. • A small structure is used for the proposed system of dimension 60 µm × 75 µm wafer. • This structure has a response time of 3.5 ps. • All-optical combinational/ sequential systems can be realized from the implemented system. The authors demonstrate an all-optical Fredkin gate which implements an interference based controlled swap operation. This realization has a small footprint (60 µm × 75 µm wafer size), and in this scheme, the phase shifts are achieved by the variation of the path length of the light necessary for the operation. For the simulation, the wavelength used is 1550 nm. This reversible logic gate optimizes the power requirement and have a non-dissipative operation. PWE and FDTD methods are used for the simulation process. The novelty of the proposed research work is that the implementation of the Fredkin gate is organized only by the constructive/destructive interferences of the light. No nonlinear switching is used to do it and hence the speed of operation goes faster than most of the the Fredkin gates in PhCs using non linearities and it proposes a very good contrast ratio. [ABSTRACT FROM AUTHOR]