Quantum Optical Tristate Hadamard Gate Using Phase Encoding Principle on Photonic Crystal

Researchers have reported two-state quantum Hadamard gate using different optical techniques. In this paper, authors propose a new concept for developing the tristate form of single qubit quantum Hadamard gate using phase encoding technique of light. Phase differences are generated by using electro-optic modulators of appropriate biasing voltages. The circuits are reversible and satisfy the quantum requirements. A similar system is also designed on 2D photonic bandgap crystal-based layout with footprint area 337.5 µm². The cylindrical rods of refractive index 3.45 are inserted on air substrate to design the layout. The operation of the system is simulated by finite difference time domain (FDTD) method. Desired phase values are obtained by varying the optical path length in the channels. The maximum response time of the system is observed to be 0.125 ps which is very useful in superfast quantum computing and data processing.