Magnon squeezing enhanced ground-state cooling in cavity magnomechanics

TL;DR

This paper demonstrates that magnon squeezing, achieved through magnon self-Kerr nonlinearity, significantly enhances ground-state cooling of mechanical vibrations in cavity magnomechanics, especially in regimes where traditional methods are ineffective.

Contribution

It introduces a novel approach using magnon squeezing to improve ground-state cooling in cavity magnomechanics, particularly in the unresolved-sideband regime.

Findings

Magnon squeezing suppresses magnomechanical Stokes scattering.

Magnon squeezing enables ground-state cooling in unresolved-sideband regime.

Coupling to microwave cavity has an adverse effect on cooling.

Abstract

Cavity magnomechanics has recently become a new platform for studying macroscopic quantum phenomena. The magnetostriction induced vibration mode of a large-size ferromagnet or ferrimagnet reaching its ground state represents a genuine macroscopic quantum state. Here we study the ground-state cooling of the mechanical vibration mode in a cavity magnomechanical system, and focus on the role of magnon squeezing in improving the cooling efficiency. The magnon squeezing is obtained by exploiting the magnon self-Kerr nonlinearity. We find that the magnon squeezing can significantly and even completely suppress the magnomechanical Stokes scattering. It thus becomes particularly useful in realizing ground-state cooling in the unresolved-sideband regime, where the conventional sideband cooling protocols become inefficient. We also find that the coupling to the microwave cavity plays only an adverse effect in mechanical cooling. This makes essentially the two-mode magnomechanical system (without involving the microwave cavity) a preferred system for cooling the mechanical motion, in which the magnon mode is established by a uniform bias magnetic field and a microwave drive field.