Silicon nitride membrane resonators at millikelvin temperatures with quality factors exceeding $10^8$

TL;DR

This study demonstrates silicon nitride membrane resonators achieving ultra-high quality factors exceeding 10^8 at millikelvin temperatures, opening new avenues for quantum optomechanics and photon conversion applications.

Contribution

It reports the first observation of quality factors surpassing 10^8 in silicon nitride membranes at millikelvin temperatures, significantly advancing low-dissipation mechanical resonator technology.

Findings

Quality factors exceed 10^8 at 14 mK

Q increases divergingly below 200 mK

Membranes are suitable for quantum optomechanics

Abstract

We study mechanical dissipation of the fundamental mode of millimeter-sized, high quality-factor ($Q$) metalized silicon nitride membranes at temperatures down to 14 mK using a three-dimensional optomechanical cavity. Below 200 mK, high-$Q$ modes of the membranes show a diverging increase of $Q$ with decreasing temperature, reaching $Q=1.27\times10^8$ at 14 mK, an order of magnitude higher than reported before. The ultra-low dissipation makes the membranes highly attractive for the study of optomechanics in the quantum regime, as well as for other applications of optomechanics such as microwave to optical photon conversion.