Phonon engineering in proximity enhanced superconductor heterostructures

Yong-Chao Tang; Sangil Kwon; Hamid R Mohebbi; David G Cory; Guo-Xing Miao

doi:10.1038/s41598-017-04057-1

Phonon engineering in proximity enhanced superconductor heterostructures

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

Authors

Yong-Chao Tang^{1

2}, Sangil Kwon^{3

4}, Hamid R Mohebbi³, David G Cory^{3

4

5

6

7}, Guo-Xing Miao^{8

3}

Affiliations

¹ Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada. yongchao.tang@uwaterloo.ca.
² Institute for Quantum Computing, University of Waterloo, Waterloo, ON, N2L 3G1, Canada. yongchao.tang@uwaterloo.ca.
³ Institute for Quantum Computing, University of Waterloo, Waterloo, ON, N2L 3G1, Canada.
⁴ Department of Physics, University of Waterloo, Waterloo, ON, N2L 3G1, Canada.
⁵ Department of Chemistry, University of Waterloo, Waterloo, ON, N2L 3G1, Canada.
⁶ Perimeter Institute for Theoretical Physics, Waterloo, ON, N2L 2Y5, Canada.
⁷ Canada Institute for Advanced Research, Toronto, ON, M5G 1Z8, Canada.
⁸ Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, ON, N2L 3G1, Canada.

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.

Publication types

Research Support, Non-U.S. Gov't