Year: 2012
Type: article
Abstract: We have fabricated and measured Josephson junction (JJ) defect spectrometers, which are frequency-tunable, nearly harmonic oscillators that probe strongly coupled two-level systems (TLSs) in the barrier of a JJ. The JJDSs accommodate a wide range of junction inductances, LJ, while maintaining a resonance frequency, fres, in the range of 4–8 GHz. By applying a magnetic flux bias to tune fres, we detect strongly coupled TLSs in the junction barrier as splittings in the device spectrum. JJDSs fabricated with a via-style Al/thermal AlOx/Al junction and measured between 30–45 mK with single-photon excitation levels show a density of TLSs in the range σTLSh≈0.4-0.5/GHzμm2, and a junction loss tangent of tanδJ≈2.9×10−3.
Source: Applied Physics Letters
DOI: 10.1063/1.4744901
Authors: M. J. A. Stoutimore, M. S. Khalil, C. J. Lobb, K. D. Osborn
Institutions: University of Maryland, College Park, Joint Quantum Institute
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W1977518449