Deterministic quantum entanglement operations on the polarization degrees of freedom of an optical photon and a microwave photon

Abstract The polarization degrees of freedom (DOF) are one of the most widely utilized photonic DOF in quantum communication. Nevertheless, superconducting quantum system, which has emerged as a prominent solid-state platform for local quantum computing (QC), exhibit inherent limitations in processing the polarization DOF of microwave photons (MPs). This fundamental constraint presents a challenge in establishing efficient interfaces between local superconducting QC and optical quantum communication. In this paper, we present the input–output relationships of the polarization DOF of photons and MPs for a hybrid system composed of a nitrogen-vacancy ensemble, an optical cavity, and a superconducting resonator. By utilizing these relationships, we propose schemes for the generation of Bell-state entanglement and the implementation of a controlled-NOT gate based on the polarization DOF of an optical photon and a MP. With experimentally feasible parameters, both the fidelities and efficiencies of our schemes can exceed 99.9%. This also makes hyperparallel quantum information processing based on optical photons and MPs possible.