Implementation of two-qubit reversible SWAP gate in Photonic crystal

Quantum SWAP gate is a two-qubit logic gate which can switch quantum states by rearranging their qubits. In this paper, authors propose a novel structure for two-qubit reversible SWAP gate in micro-domain using Photonic crystal. The proposed structure of SWAP gate is designed in a small footprint area of 122.85 μm² which can be used in optical integrated circuits. The same structure can be utilized to process both the intensity encoded qubits and frequency encoded qubits. Frequency encoding method reduces the possibility of information loss significantly. The proposed system is simulated by finite difference time domain (FDTD) method to verify its performance. The response time of the system is 80 fs only, which ensures a superfast computing and data processing ability with this structure. The extinction ratio of the circuit is also very high. Qubit swapping technique of SWAP gate can be utilized to develop many other quantum logic gates and all-optical circuits in qunit system.