# Enhancement of antiferromagnetic magnon-magnon entanglement by cavity cooling

## TL;DR

This paper demonstrates that cavity cooling can significantly enhance magnon-magnon entanglement in an antiferromagnetic system, providing a pathway for quantum manipulation in cavity spintronics.

## Contribution

It reveals that cavity coupling enhances magnon-magnon entanglement while magnon-photon entanglement remains negligible, and explains this through cavity-induced cooling physics.

## Key findings

- Magnon-magnon entanglement is strong and can be enhanced by cavity coupling.
- Maximum entanglement occurs at antiferromagnet resonance with light.
- Cavity cooling near the joint vacuum state explains entanglement enhancement.

## Abstract

Magnon-photon coupling has been experimentally realized inside a cavity and the emerging field known as cavity spintronics has attracted significant attention for its potential docking with quantum information science. However, one seldom knows whether this coupling implies an entanglement state among magnons and photons or not, which is crucial for its usage in quantum information. Here we study the entanglement properties among magnons and photons in an antiferromagnet-light system and find that the entanglement between magnon and photon is nearly zero while the magnon-magnon entanglement is very strong and it can be even further enhanced through the coupling with the cavity photons. The maximum enhancement occurs when the antiferromagnet reaches resonant with the light. The essential physics can be well understood within the picture of cavity induced cooling of magnon-magnon state near its joint vacuum with stronger entanglement. Our results are significant to extend the cavity spintronics to quantum manipulation and further provide an alternate to manipulate the deep strong correlations of continuous variable entanglement with a generic stable condition and easy tunability.