Single-photon cooling in microwave magneto-mechanics

TL;DR

This paper demonstrates a magnetically coupled microwave optomechanical system achieving a significant single-photon coupling strength, enabling cooling of a massive mechanical resonator and advancing towards quantum state preparation.

Contribution

The authors introduce a novel magnetically coupled microwave optomechanical system with enhanced coupling strength and cooperativity, surpassing previous microwave optomechanics capabilities.

Findings

Achieved a single-photon coupling of ~3 kHz, ten times higher than previous systems.

Measured a large single-photon cooperativity with C0 ≥ 10.

Successfully cooled the mechanical resonator to one-third of its phonon population.

Abstract

Cavity optomechanics, where photons are coupled to mechanical motion, provides the tools to control mechanical motion near the fundamental quantum limits. Reaching single-photon strong coupling would allow to prepare the mechanical resonator in non-Gaussian quantum states. Preparing massive mechanical resonators in such states is of particular interest for testing the boundaries of quantum mechanics. This goal remains however challenging due to the small optomechanical couplings usually achieved with massive devices. Here we demonstrate a novel approach where a mechanical resonator is magnetically coupled to a microwave cavity. We measure a single-photon coupling of $g_0/2 \pi \sim 3$ kHz, an improvement of one order of magnitude over current microwave optomechanical systems. At this coupling we measure a large single-photon cooperativity with $C_0 \gtrsim 10$, an important step to reach single-photon strong coupling. Such a strong interaction allows us to cool the massive mechanical resonator to a third of its steady state phonon population with less than two photons in the microwave cavity. Beyond tests for quantum foundations, our approach is also well suited as a quantum sensor or a microwave to optical transducer.