Abstract
In this paper, we propose employing electron scattering to realize unitary quantum gates that are controlled by three qubits. Using Feynman's rules, we find an expression for the transition amplitude for scattering from an external electromagnetic source. In this context, the scattering amplitude is modeled as a unitary gate whose state can be regulated. The optimal value of the vector potential needed to implement the gate is obtained by minimizing the difference between the designed gate and the target gate, with the total energy consumed as a constraint. The design algorithm is obtained by discretizing the resulting integral equations into vector equations. This design algorithm can be applied in various fields such as quantum computing, communication, and sensing. It offers a promising approach for developing efficient and accurate gates for quantum information processing. Furthermore, this approach can also be extended to design gates for multi-qubit systems, which are essential for large-scale quantum computing. The use of this algorithm can significantly contribute to the development of practical quantum technologies.