Amplification of waves from a rotating body
Amplification of waves from a rotating body
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DOI：
10.1038/s41567-020-0944-3
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发表时间：
2020-06-22
期刊：
影响因子：
19.6
通讯作者：
Faccio, Daniele
中科院分区：
文献类型：
--
作者：
Cromb, Marion;Gibson, Graham M.;Faccio, Daniele
当旋转速率超过入射波的频率时，携带轨道角动量的声波在穿过吸收盘时会被放大，从而提供了泽尔多维奇放大的实验证明。1971年，泽尔多维奇预测量子涨落和经典波从旋转的吸收圆柱体反射会获得能量并被放大。这一概念是理解黑洞可能放大量子涨落的关键一步，但由于具有挑战性的实验要求，即圆柱旋转速率必须大于入射波频率，因此尚未得到实验验证。在这里，我们通过实验证明，这些条件可以满足声波。我们表明，低频声学模式的轨道角动量传输通过吸收旋转磁盘和放大高达30%或更多时，磁盘旋转速率满足Zel'dovich条件。这些实验解决了基础物理学中的一个突出问题，并对未来从旋转系统中提取能量的研究产生了影响。
Acoustic waves that carry orbital angular momentum are amplified as they pass through an absorbing disk when the rotation rate exceeds the frequency of the incident wave, thus providing an experimental demonstration of Zel'dovich amplification.In 1971, Zel'dovich predicted that quantum fluctuations and classical waves reflected from a rotating absorbing cylinder will gain energy and be amplified. This concept, which is a key step towards the understanding that black holes may amplify quantum fluctuations, has not been verified experimentally owing to the challenging experimental requirement that the cylinder rotation rate must be larger than the incoming wave frequency. Here, we demonstrate experimentally that these conditions can be satisfied with acoustic waves. We show that low-frequency acoustic modes with orbital angular momentum are transmitted through an absorbing rotating disk and amplified by up to 30% or more when the disk rotation rate satisfies the Zel'dovich condition. These experiments address an outstanding problem in fundamental physics and have implications for future research into the extraction of energy from rotating systems.