Regensburg 2016 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 51: Superconductivity: Tunneling, Josephson Junctions, SQUIDs

TT 51.2: Talk

Wednesday, March 9, 2016, 15:15–15:30, H19

Microwave resonators with high kinetic inductance made from superconducting AlO_x — •Sebastian T. Skacel¹, Micha Wildermuth¹, Julian Münzberg¹, Jan N. Voss¹, Marco Pfirrmann¹, Lucas Radtke¹, Sebastian Probst¹, Martin Weides^1,2, Hannes Rotzinger¹, and Alexey V. Ustinov¹ — ¹Physikalisches Institut, Karlsruher Institut für Technologie, D-76131 Karlsruhe, Germany — ²Institute of Physics, Johannes Gutenberg University Mainz, D-55128 Mainz, Germany

We present superconducting resonators made out of AlO_x with a kinetic inductance fraction - the ratio between kinetic and total inductance of the resonator - close to unity and high quality factors. We show measurements of coplanar waveguide resonators with ultra high impedances and therefore allowing for compact design in the microwave regime. For instance, a coplanar λ/4 type resonator with resonance frequency of about 5 GHz can be reduced to a length of 180 µm. The resonator impedance depends on the geometry, i.e. length and the width of the central conductor, and its missmatch factor with the 50 Ω feedline changes from about 5 to 30. This also influences the resonator quality factor, due to the altered coupling.
The resonators are fabricated in a simple single layer process starting with the sputter deposited aluminium oxide (AlO_x) on a silicon substrate, followed by optical lithography and reactive ion etch process.