南京大学学报(自然科学版) ›› 2015, Vol. 51 ›› Issue (6): 11201125.
李国龙1,任中洲1,2,3
Li Guolong1, Ren Zhongzhou1,2,3*
摘要: 在晶体中,杂质原子或晶格缺陷形成的二能级系统会对声子产生弹性散射。利用压电晶体作为共振腔的低温声腔中,这种散射过程的存在导致高频泛音的损失。这种散射可以解释为压电晶体中应变场与二能级系统的耦合,并且能够用一个相互作用哈密顿量描述。根据这个相互作用哈密顿量和二阶微扰论,我们得到了一个基于声子-二能级系统弹性散射的声子损失公式。根据这个公式,我们得到了声波损失如何受声波频率和环境温度的变化,而这种分析给出了一个合理的损失机制,解释了最近一个测量高频泛音品质因子的实验[M. Goryachev et al., Phys. Rev. Lett. 111, 085502 (2013)]。我们希望我们的工作可以为降低低温声腔激发的高频声波损失提供了理论支持。
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