Quantum Friction in Nanomechanical Oscillators at Millikelvin Temperatures

TL;DR

This study investigates quantum friction effects in nanomechanical oscillators at millikelvin temperatures, revealing dissipation dominated by quantum two-level systems and showing similarities to glass sound attenuation.

Contribution

First measurement of quantum friction in nanomechanical oscillators at millikelvin temperatures, linking dissipation to two-level systems in a novel nanoscale context.

Findings

Dissipation and frequency shift exhibit reproducible features at millikelvin temperatures.

Dissipation is dominated by internal quantum friction from approximately 50 two-level systems.

Results are consistent with sound attenuation in disordered glasses and larger silicon oscillators.

Abstract

We report low-temperature measurements of dissipation in megahertz-range, suspended, single-crystal nanomechanical oscillators. At millikelvin temperatures, both dissipation (inverse quality factor) and shift in the resonance frequency display reproducible features, similar to those observed in sound attenuation experiments in disordered glasses and consistent with measurements in larger micromechanical oscillators fabricated from single-crystal silicon. Dissipation in our single-crystal nanomechanical structures is dominated by internal quantum friction due to an estimated number of roughly 50 two-level systems, which represent both dangling bonds on the surface and bulk defects.