局部加热到熔点的低温冷却硅悬臂梁的热噪声
Thermal noise of a cryo-cooled silicon cantilever locally heated up to its melting point
摘要：
涨落耗散定理（FDT）是估计平衡态物理系统热噪声的有力工具。然而，一般来说，热平衡是一种近似，或者根本不能假设。然后需要一个更一般的FDT公式来描述波动的行为。在我们的实验中，我们研究了一个微悬臂梁被一个强热流所引起的平衡，该热流是由激光的光的吸收所产生的。当基座保持在低温时，尖端被加热到熔点，从而产生系统可以承受的最高温差。我们独立地估计悬臂梁的温度分布和它的机械波动，以及它的耗散。然后，我们证明了如何的所有观察到的自由度的热波动，虽然随着热通量的增加，是远远低于预期的系统的平均温度。我们解释这些结果由于一个最小的扩展FDT：这种缺乏热噪声产生的耗散之间共享的箝位损耗和分布式阻尼。
英文摘要：
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 micro-cantilever brought out-ofequilibrium 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 thanks to a minimal extension of the FDT: this dearth of thermal noise arises from a dissipation shared between clamping losses and distributed damping.
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