Implementation of all‐optical Toffoli gate by 2D Si–air photonic crystal.

The quantum Toffoli gate is one of the essential reversible universal logic gates widely used for optical data processing. Herein, a new scheme of developing all‐optical Toffoli gate using a two‐dimensional silicon–air photonic crystal is proposed. For the realization of the Toffoli gate, the principles of constructive and destructive interference of light are used. The Toffoli gate comprises two‐input–three‐output‐based optical AND gate, and a two‐input–one‐output optical XOR gate. Two Y junction power splitters have been used at the two inputs of the AND gate. The operating wavelength of the proposed Toffoli gate is 1550 nm along with the wafer size of 50 µm × 50 µm. The performance of the Toffoli gate has been analysed and simulated by the plane‐wave expansion method and finite‐difference time‐domain method. The response time and contrast ratios are also obtained from the simulation. The proposed Toffoli gate is intensity encoded with no non‐linear material within the crystal which shows significant improvement over other proposals. [ABSTRACT FROM AUTHOR]