Poignand Gaelle, Olivier Come, Penelet Guillaume
Laboratoire d'Acoustique de l'Université du Mans (LAUM), UMR-CNRS 6613, Institut d'Acoustique-Graduate School (IA-GS), CNRS, Le Mans Université, France.
J Acoust Soc Am. 2021 Mar;149(3):1913. doi: 10.1121/10.0003708.
This paper deals with the experimental study of an acoustic Parity-Time (PT) symmetric system based on the thermoacoustic amplification process. Such a system is presented and consists of two acoustic units connected through side branches to a waveguide. One unit contains a thermoacoustic core that provides an acoustic gain which balances the thermal and viscous losses taking place in the second unit. Two control parameters are set to adjust the impedance of the two units and thereby achieve the PT-symmetry condition. The results show that a good balance between gain and loss is achieved within a frequency range from 45 Hz to 60 Hz. The spontaneous PT-symmetry breaking and the existence of exceptional points, which are characteristic of the behavior of PT-symmetric systems, are explored in this frequency range. Moreover, the distance between the two units is shown to be a control parameter to slightly shift the frequency at which the exceptional points occur.
本文研究了基于热声放大过程的声学宇称时间（PT）对称系统的实验。文中介绍了这样一个系统，它由两个声学单元组成，这两个单元通过侧支连接到一个波导。其中一个单元包含一个热声核心，该核心提供声学增益，以平衡在第二个单元中发生的热损耗和粘性损耗。设置了两个控制参数来调整两个单元的阻抗，从而实现PT对称条件。结果表明，在45赫兹至60赫兹的频率范围内实现了增益与损耗之间的良好平衡。在该频率范围内探索了PT对称系统行为所特有的自发PT对称破缺和奇异点的存在。此外，两个单元之间的距离被证明是一个控制参数，可略微移动奇异点出现的频率。
