Soft-clamped silicon nitride string resonators at millikelvin temperatures

Abstract

We demonstrate that soft-clamped silicon nitride strings with large aspect ratio can be operated at \si{\milli\kelvin} temperatures. The quality factors ($Q$) of two measured devices show consistent dependency on the cryostat temperature, with soft-clamped mechanical modes reaching $Q>10^9$ at $46\mathrm{mK}$. For low optical readout power, $Q$ is found to saturate, indicating good thermalization between the sample and the stage it is mounted on. Our best device exhibits a force sensitivity of $9.6\mathrm{zN}/\sqrt{\mathrm{Hz}}$ and a thermal decoherence time of $0.38\mathrm{s}$ which bode well for future applications such as nanomechanical force sensing and beyond.

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Cited by in corpus (1)

• Near-resonant nuclear spin detection with megahertz mechanical resonators