标题： 纳米尺度多模态超流声学中的湍流耗散耦合 显示英文标题

标题： Turbulent dissipative coupling in nanoscale multimode superfluid acoustics

摘要： 超流体氦，即液态⁴He的无粘性低温相，由于粘度消失，使得可以构建亚微米流动通道，从而能够研究维度降低的流动。在这样的强约束体积中充满超流体，纵向声波是压力和熵密度的耦合涨落，称为第四声。在本工作中，我们使用纳米超流体声学谐振器内的多个第四声声学模式，在泵浦-探测配置中观察到量子涡旋的局域簇，导致二维湍流。局域湍流实现了声学模式之间的可控和不对称耗散耦合。此外，我们推导了一个通用程序，用于解析估计具有机械柔顺壁的体积内的超流体声学共振频率。我们的工作证实了先前的假设，即类似纳米流体系统的湍流最初在高剪切区域发展。本文提出的多模态泵浦-探测方法将允许未来的实验研究二维量子湍流的动力学，例如自由衰减。 显示英文摘要

摘要： Superfluid helium, the inviscid low-temperature phase of liquid \4He, enables investigation of flows with reduced dimensionality since, due to the vanishing viscosity, sub-micron flow channels can be constructed. In such strongly confined volumes filled with superfluid, the longitudinal acoustic wave is a coupled fluctuation of pressure and entropy density called fourth sound. In this work, we use multiple 4th sound acoustic modes inside a nano-superfluidic acoustic resonator in a pump-probe arrangement to observe localized clusters of quantized vortices leading to two-dimensional turbulence. The localised turbulence enables controllable and asymmetric dissipative coupling between acoustic modes. Furthermore, we derive a general procedure for analytically estimating the superfluid acoustic resonance frequencies inside a volume with mechanically compliant walls. Our work confirms earlier assumptions that turbulence in similar nanofluidic systems initially develops in localized areas of high shear. The multimode pump-probe methods presented here will allow future experiments to study the dynamics of two-dimensional quantum turbulence, e.g., the free decay.