Entangling two distant non-interacting microwave modes

TL;DR

This paper introduces a protocol for entangling two distant microwave modes using opto-electro-mechanical systems, enabling quantum networking with local optical measurements to verify entanglement.

Contribution

It extends continuous variable entanglement swapping to microwave modes, utilizing hybrid systems to overcome microwave photon fragility and enable remote quantum entanglement.

Findings

Successful protocol for remote microwave entanglement

Entanglement verification with local optical measurements

Potential for quantum networks connecting solid-state qubits

Abstract

We propose a protocol able to prepare two remote and initially uncorrelated microwave modes in an entangled stationary state, which is certifiable using only local optical homodyne measurements. The protocol is an extension of continuous variable entanglement swapping, and exploits two hybrid quadripartite opto-electro-mechanical systems in which a nanomechanical resonator acts as a quantum interface able to entangle optical and microwave fields. The proposed protocol allows to circumvent the problems associated with the fragility of microwave photons with respect to thermal noise and may represent a fundamental tool for the realization of quantum networks connecting distant solid-state and superconducting qubits, which are typically manipulated with microwave fields. The certifying measurements on the optical modes guarantee the success of entanglement swapping without the need of performing explicit measurements on the distant microwave fields.