Heralded hyperparallel Fredkin gate with robust fidelity

Abstract

We propose a heralded hyperparallel Fredkin gate for a three-photon system with the help of the optical property of a quantum dot (QD) embedded in a microcavity. This hyper-Fredkin gate performing both on spatial and polarized degrees of freedom (DoFs) of the three-photon system is equal to double independent three-photon Fredkin gate in one DoF, which has advantages over consuming a less quantum resource, accelerating calculation speed, and inhibiting photon-dissipation noise. Meanwhile, the fidelity of our hyper-Fredkin gate, in principle, approach unit even for the non-identical QD-cavity systems, as the imperfections involved in practical input–output processes of three photons can be converted into heralded errors by clicking the detectors rather than infidelity. Furthermore, the flexibility of the gate can be directly extended to construct some types of hybrid hyper-Fredkin gates with the same high fidelity and efficiency, accessibly performed under existing experimental techniques, as well as used large-scale quantum information processing.