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Distribution of two-level system couplings to strain and electric fields in glasses at low temperatures
Physical Review B ( IF 3.7 ) Pub Date : 2021-10-26 , DOI: 10.1103/physrevb.104.134203
Herve M. Carruzzo , Alexander Bilmes , Jürgen Lisenfeld , Zheng Yu , Bu Wang , Zhongyi Wan , J. R. Schmidt , Clare C. Yu

The thermal, acoustic, and dielectric properties of glasses below 1 K are dictated by the interaction of two-level systems (TLS) with strain and electric fields. In a previous paper, we proposed a modified TLS model to quantitatively account for the universally small phonon scattering in glasses at low temperatures. A key ingredient of this model was a wide distribution of couplings between TLS and phonons, contrary to the standard model which assumes a single averaged value is sufficient. In this paper, we expand on this view and include couplings to strain as well as electric fields. We then compare our theoretical results to measurements obtained using superconducting qubits. We find that the predictions of the modified TLS model are more consistent with experiments than those of the standard model. For the distribution of couplings between TLS and the strain field, there is a better agreement with experiments if we include a random distribution of local strains. Such a distribution of local strains is consistent with those found from molecular dynamics simulations.

中文翻译:

低温下玻璃中应变和电场的两级系统耦合分布

低于 1 K 的玻璃的热、声和介电特性由两级系统 (TLS) 与应变和电场的相互作用决定。在之前的一篇论文中,我们提出了一种改进的 TLS 模型来定量解释低温下玻璃中普遍较小的声子散射。该模型的一个关键要素是 TLS 和声子之间广泛分布的耦合,这与假设单个平均值就足够的标准模型相反。在本文中,我们扩展了这一观点,并包括了应变和电场的耦合。然后,我们将我们的理论结果与使用超导量子位获得的测量结果进行比较。我们发现修改后的 TLS 模型的预测比标准模型的预测更符合实验。对于 TLS 和应变场之间的耦合分布,如果我们包括局部应变的随机分布,则与实验的一致性更好。这种局部应变的分布与从分子动力学模拟中发现的分布一致。
更新日期:2021-10-26
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