近日，日本大阪大学的Yosuke Minowa及其研究团队取得一项新进展。经过不懈努力，他们在量子化旋涡上实现开尔文波的直接激发。相关研究成果已于2025年1月13日在国际知名学术期刊《自然—物理学》上发表。
该研究团队介绍了一种在超流氦-4中的量子化涡旋上激发开尔文波的受控方法。研究人员利用一个在时变电场驱动下振荡的带电纳米粒子，来激励涡旋上的开尔文波。通过三维图像重建，研究人员证实了开尔文波的螺旋性质，并直观地展示了其复杂的动力学行为。
此外，研究人员还确定了开尔文波的色散关系和相速度，并确定了涡量的方向，从而加深了对量子流体行为的理解。这项工作阐明了开尔文波的动力学特性，并开创了一种在三维空间中操纵和观察量子化涡旋的方法，为探索量子流体系统开辟了新的途径。
据悉，螺旋和螺线形在多种物理系统中普遍存在，它们凭借其固有的简洁性和手性特征，在表征对称性、描述动力学以及实现独特功能方面发挥着至关重要的作用。量子化涡旋上的螺旋激发，即开尔文波，就是这样一个物理系统的例证。开尔文波在无黏性量子流体中的能量耗散过程中起着关键作用。然而，有意激发开尔文波已被证明是一项颇具挑战的任务。
附：英文原文
Title: Direct excitation of Kelvin waves on quantized vortices
Author: Minowa, Yosuke, Yasui, Yuki, Nakagawa, Tomo, Inui, Sosuke, Tsubota, Makoto, Ashida, Masaaki
Issue&Volume: 2025-01-13
Abstract: Helices and spirals, prevalent across various physical systems, play a crucial role in characterizing symmetry, describing dynamics and enabling unique functionalities, all stemming from their inherent simplicity and chiral nature. Helical excitations on quantized vortices, referred to as Kelvin waves, are one example of such a physical system. Kelvin waves play a vital role in energy dissipation within inviscid quantum fluids. However, deliberately exciting Kelvin waves has proven to be challenging. Here we introduce a controlled method for exciting Kelvin waves on a quantized vortex in superfluid helium-4. We used a charged nanoparticle that oscillates when driven by a time-varying electric field to stimulate Kelvin waves on the vortex. Confirmation of the helical nature of Kelvin waves was achieved through three-dimensional image reconstruction, which provided visual evidence of their complex dynamics. Additionally, we determined the dispersion relation and the phase velocity of the Kelvin wave and identified the vorticity direction, thus enhancing our understanding of quantum fluid behaviour. This work elucidates the dynamics of Kelvin waves and initiates an approach for manipulating and observing quantized vortices in three dimensions, thereby opening avenues for exploring quantum fluidic systems.
DOI: 10.1038/s41567-024-02720-9
Source: https://www.nature.com/articles/s41567-024-02720-9