Implementations of more general solid-state (SWAP)${}^1/m$ and controlled-(swap)${}^1/m$ gates

Abstract

Universal quantum gates are the core elements in quantum information processing. We design two schemes to realize more general (SWAP)${}^{1/m}$ and controlled--(swap)${}^{1/m}$ gates (for integer $m\ge 1$) by directing flying single photons to solid--state quantum dots. The parameter $m$ is easily controlled by adjusting two quarter--wave plates and one half--wave plate. Additional computational qubits are not required to construct the two gates. Evaluations of the gates indicate that our proposals are feasible with current experimental technology.