# Hybrid quantum gates between flying photon and diamond nitrogen-vacancy centers assisted by optical microcavities

## TL;DR

This paper proposes compact, high-fidelity quantum circuits for implementing universal gates between flying photons and diamond NV centers, enhancing quantum information processing capabilities.

## Contribution

It introduces novel, resource-efficient schemes for deterministic three-qubit gates between photons and NV centers using microcavities, without additional qubits.

## Key findings

- High fidelities and efficiencies demonstrated
- Schemes are feasible in experimental setups
- Reduced complexity compared to traditional methods

## Abstract

Hybrid quantum gates hold great promise for quantum information processing since they preserve the advantages of different quantum systems. Here we present compact quantum circuits to deterministically implement controlled-NOT, Toffoli, and Fredkin gates between a flying photon qubit and diamond nitrogen-vacancy (NV) centers assisted by microcavities. The target qubits of these universal quantum gates are encoded on the spins of the electrons associated with the diamond NV centers and they have long coherence time for storing information, and the control qubit is encoded on the polarizations of the flying photon and can be easily manipulated. Our quantum circuits are compact, economic, and simple. Moreover, they do not require additional qubits. The complexity of our schemes for universal three-qubit gates is much reduced, compared to the synthesis with two-qubit entangling gates. These schemes have high fidelities and efficiencies, and they are feasible in experiment.