Abstract
The Fluctuation-Dissipation Theorem (FDT) is a powerful tool to estimate the thermal noise of physical systems in equilibrium. In general, however, thermal equilibrium is an approximation or cannot be assumed at all. A more general formulation of the FDT is then needed to describe the behavior of the fluctuations. In our experiment we study a microcantilever brought out of equilibrium by a strong heat flux generated by the absorption of the light of a laser. While the base is kept at cryogenic temperatures, the tip is heated up to the melting point, thus creating the highest temperature difference the system can sustain. We independently estimate the temperature profile of the cantilever and its mechanical fluctuations as well as its dissipation. We then demonstrate how the thermal fluctuations of all the observed degrees of freedom, though increasing with the heat flux, are much lower than what is expected from the average temperature of the system. We interpret these results using a minimal extension of the FDT: this dearth of thermal noise arises from a dissipation shared between clamping losses and distributed damping.
- Received 19 January 2021
- Accepted 27 April 2021
DOI:https://doi.org/10.1103/PhysRevE.103.062125
©2021 American Physical Society
Physics Subject Headings (PhySH)
synopsis
Cantilever Experiments Update Description of Thermal Noise
Published 15 June 2021
Multiple sources of mechanical dissipation seem to explain why a cantilever subject to an extreme temperature gradient has less thermal noise than theory predicts.
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