[Paper Review] Microwave-optics Entanglement via Cavity Optomagnomechanics

Zhiyuan Fan, Liu Qiu+2 more|arXiv (Cornell University)|Aug 23, 2022

Mechanical and Optical Resonators4 citations

TL;DR

This paper proposes a cavity optomagnomechanical system that generates stationary microwave-optics entanglement via dispersive magnetostrictive and radiation-pressure interactions. By leveraging magnomechanical parametric down-conversion and effective optomechanical beamsplitter and electromagnonic state-swap interactions, the system achieves robust entanglement between microwave and optical fields, even at temperatures up to 380 mK.

ABSTRACT

Microwave-optics entanglement is a vital component for building hybrid quantum networks. Here, a new mechanism for preparing stationary entanglement between microwave and optical cavity fields in a cavity optomagnomechanical system is proposed. It consists of a magnon mode in a ferrimagnetic crystal that couples directly to a microwave cavity mode via the magnetic dipole interaction, and indirectly to an optical cavity through the deformation displacement of the crystal. The mechanical displacement is induced by the magnetostrictive force and coupled to the optical cavity via radiation pressure. Both the opto- and magnomechanical couplings are dispersive. Magnon-phonon entanglement is created via magnomechanical parametric down-conversion, which is further distributed to optical and microwave photons via simultaneous optomechanical beamsplitter interaction and electromagnonic state-swap interaction, yielding stationary microwave-optics entanglement. The microwave-optics entanglement is robust against thermal noise, which will find broad potential applications in quantum networks and quantum information processing with hybrid quantum systems.

Motivation & Objective

• To develop a scalable mechanism for generating stationary microwave-optics entanglement in hybrid quantum systems.
• To address the challenge of large frequency mismatch between microwave and optical domains in quantum networks.
• To leverage magnetostrictive and radiation-pressure interactions for efficient entanglement transfer.
• To ensure robustness against thermal noise and mechanical damping in practical operating conditions.
• To demonstrate a feasible platform for integrating microwave and optical quantum nodes via a single mechanical resonator.

Proposed method

• The system employs a ferrimagnetic YIG crystal with a magnon mode dispersively coupled to a microwave cavity via magnetic dipole interaction.
• The magnon mode couples to a mechanical vibration mode via magnetostrictive force, enabling dispersive magnomechanical coupling.
• The mechanical mode couples to an optical cavity via radiation pressure, establishing dispersive optomechanical interaction.
• Entanglement is generated via magnomechanical parametric down-conolation, creating magnon-phonon entanglement.
• This entanglement is transferred to microwave and optical fields through effective optomechanical beamsplitter and electromagnonic state-swap interactions.
• The system operates under resolved-sideband conditions with optimized detunings to maximize entanglement and ensure stability.

Experimental results

Research questions

• RQ1 Can stationary microwave-optics entanglement be generated in a cavity optomagnomechanical system using dispersive interactions?
• RQ2 How does the entanglement robustness depend on temperature and mechanical damping in the system?
• RQ3 What are the optimal working conditions (detunings, coupling strengths) for maximizing microwave-optics entanglement?
• RQ4 Can the entanglement be preserved under realistic thermal and lossy conditions?
• RQ5 How does the use of a micron-sized YIG crystal enhance magnomechanical coupling compared to bulk crystals?

Key findings

• The system achieves microwave-optics entanglement with a logarithmic negativity of approximately 0.4 under optimal conditions.
• Entanglement is robust against thermal noise, surviving up to 380 mK in the presence of environmental heating.
• The mechanical mode is cooled to an effective mean phonon number of approximately 0.17, indicating ground-state cooling.
• The system remains stable under strong coupling (Gm/2π = 4.6 MHz) due to multiple dissipation channels.
• Optimal entanglement is achieved at zero cavity-magnon detuning (Δam = 0), confirming the role of coherent state transfer.
• For mechanical damping rates up to 10^5 Hz, entanglement persists up to ~0.1 K, demonstrating resilience to decoherence.