论文标题
超氟$^4 $ He作为纳米机电谐振器中不同阻尼模型的严格测试台
Superfluid $^4$He as a rigorous test bench for different damping models in nanoelectromechanical resonators
论文作者
论文摘要
我们已经使用纳米机电谐振器在不同的温度状态下探测超过$^4 $ HE，跨越了四个数量级。这些机制的特征是机制的特征，这些机制为阻尼和谐振频率的转移提供了主要贡献：在最低温度下在两个级别的系统下，在几百mk的弹道声子和rotons处隧穿，在超过超级流体过渡温度以及正常流体中的两型流体状态下的层laminar拖动。将纳米机电谐振器浸入流体中会大大增加其有效质量，从而降低了它们的谐振频率。无耗散的超级流引起了一种独特的可能性，可以极大地改变机械共振频率，从而可以对机械谐振器中不同阻尼模型进行严格的测试。我们将此方法应用来表征设备中两级系统损耗和磁性阻尼的表征。
We have used nanoelectromechanical resonators to probe superfluid $^4$He at different temperature regimes, spanning over four orders of magnitude in damping. These regimes are characterized by the mechanisms which provide the dominant contributions to damping and the shift of the resonance frequency: tunneling two level systems at the lowest temperatures, ballistic phonons and rotons at few hundred mK, and laminar drag in the two-fluid regime below the superfluid transition temperature as well as in the normal fluid. Immersing the nanoelectromechanical resonators in fluid increases their effective mass substantially, decreasing their resonance frequency. Dissipationless superflow gives rise to a unique possibility to dramatically change the mechanical resonance frequency in situ, allowing rigorous tests on different damping models in mechanical resonators. We apply this method to characterize tunneling two-level system losses and magnetomotive damping in the devices.
