声子工程在近邻增强超导异质结构中的应用。

Phonon engineering in proximity enhanced superconductor heterostructures.

机构信息

Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada.

Institute for Quantum Computing, University of Waterloo, Waterloo, ON, N2L 3G1, Canada.

出版信息

Sci Rep. 2017 Jun 27;7(1):4282. doi: 10.1038/s41598-017-04057-1.

DOI:10.1038/s41598-017-04057-1

PMID:28655894

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC5487347/

Abstract

In this research, we tailor the phonon density of states (DOS) in thin superconducting films to suppress quasiparticle losses. We examine a model system of a proximity-enhanced three-layered Al/Nb/Al heterostructure and show that the local quantized phonon spectrum of the ultrathin Al cladding layers in the heterostructure has a pronounced effect on the superconducting resonator's quality factors. Instead of a monotonic increase of quality factors with decreasing temperatures, we observe the quality factor reaches a maximum at 1.2 K in 5/50/5 nm Al/Nb/Al microstrip resonators, because of a quantized phonon ladder. The phonon DOS may be engineered to enhance the performance of quantum devices.

摘要

在这项研究中，我们通过调整超导薄膜中的声子态密度（DOS）来抑制准粒子损耗。我们研究了一个由近邻增强的三层 Al/Nb/Al 异质结构组成的模型系统，并表明异质结构中超薄 Al 覆盖层的局域量子化声子谱对超导谐振器的品质因数有显著影响。我们观察到，在 5/50/5nm Al/Nb/Al 微带谐振器中，品质因数不是随着温度的降低而单调增加，而是在 1.2K 时达到最大值，这是由于存在量子化声子梯。通过工程设计声子 DOS 可能会提高量子器件的性能。