# Heralded Generation and Detection of Entangled Microwave--Optical Photon Pairs

## TL;DR

This paper proposes a heralded scheme to generate entangled microwave-optical photon pairs using a cavity electro-optomechanical system, advancing quantum state transfer and hybrid quantum networks.

## Contribution

It introduces a novel heralded entanglement generation method that bypasses efficiency thresholds, compatible with current experimental capabilities.

## Key findings

- Scheme is feasible with recent electro-optomechanics progress
- Identifies parameter regime for entanglement verification
- Potential for generalization to other physical systems

## Abstract

Quantum state transfer between microwave and optical frequencies is essential for connecting superconducting quantum circuits to coherent optical systems and extending microwave quantum networks over long distances. To build such a hybrid `quantum Internet,' an important experiment in the quantum regime is to entangle microwave and optical modes. Based on the model of a generic cavity electro-optomechanical system, we present a heralded scheme to generate entangled microwave--optical photon pairs, which can bypass the efficiency threshold for quantum channel capacity in direct transfer protocols. The parameter regime for entanglement verification is identified that is compatible with realistic experimental settings. Our scheme is feasible given the latest experimental progress on electro-optomechanics, and can be potentially generalized to various physical systems.