190 citations · 595 across the 11 of their papers we have counts for
11 papers
Anomalous Microwave Response in YBCO Resonators beyond the Two-Level-System Model
Kaiwen Zheng, Nathan J. Johnson, Nathan T. Thobaben +5
We report the microwave response of coplanar-waveguide (CPW) resonators fabricated from (YBCO) thin films over temperatures from approximately $70~\math…
Nitrogen Plasma Passivated Niobium Resonators for Superconducting Quantum Circuits
K. Zheng, D. Kowsari, N. J. Thobaben +6
Microwave loss in niobium metallic structures used for superconducting quantum circuits is limited by a native surface oxide layer formed over a timescale of minutes when exposed t…
Fabrication and surface treatment of electron-beam evaporated niobium for low-loss coplanar waveguide resonators
D. Kowsari, K. Zheng, J. T. Monroe +6
We characterize low-loss electron-beam evaporated niobium thin films deposited under ultra-high vacuum conditions. Slow deposition yields films with a high superconducting transiti…
Optical Direct Write of Dolan--Niemeyer-Bridge Junctions for Transmon Qubits
J. T. Monroe, D. Kowsari, K. Zheng +4
We characterize highly coherent transmon qubits fabricated with a direct-write photolithography system. Multi-layer evaporation and oxidation allows us to change the critical curre…
Proximity-Coupled Ti/TiN Multilayers for use in Kinetic Inductance Detectors
Michael R. Vissers, Jiansong Gao, Martin Sandberg +4
We apply the superconducting proximity effect in TiN/Ti multi-layer films to tune the critical temperature, Tc, to within 10 mK with high uniformity (less than 15 mK spread) across…
Characterization and In-situ Monitoring of Sub-stoichiometric Adjustable Tc Titanium Nitride Growth
Michael R. Vissers, Jiansong Gao, Jeffrey S. Kline +4
The structural and electrical properties of Ti-N films deposited by reactive sputtering depend on their growth parameters, in particular the Ar:N2 gas ratio. We show that the nitro…
A titanium-nitride near-infrared kinetic inductance photon-counting detector and its anomalous electrodynamics
J. Gao, M. R. Visser, M. O. Sandberg +10
We demonstrate single-photon counting at 1550 nm with titanium-nitride (TiN) microwave kinetic inductance detectors. Energy resolution of 0.4 eV and arrival-time resolution of 1.2…
Etch Induced Microwave Losses in Titanium Nitride Superconducting Resonators
Martin Sandberg, Michael R. Vissers, Jeffrey S. Kline +4
We have investigated the correlation between the microwave loss and patterning method for coplanar waveguide titanium nitride resonators fabricated on Si wafers. Three different me…
Coherence in a transmon qubit with epitaxial tunnel junctions
Martin P. Weides, Jeffrey S. Kline, Michael R. Vissers +5
We developed transmon qubits based on epitaxial tunnel junctions and interdigitated capacitors. This multileveled qubit, patterned by use of all-optical lithography, is a step towa…
Sub-micrometer epitaxial Josephson junctions for quantum circuits
Jeffrey S. Kline, Michael R. Vissers, Fabio C. S. da Silva +11
We present a fabrication scheme and testing results for epitaxial sub-micrometer Josephson junctions. The junctions are made using a high-temperature (1170 K) "via process" yieldin…
Low Loss Superconducting Titanium Nitride Coplanar Waveguide Resonators
Michael R. Vissers, Jiansong Gao, David S. Wisbey +5
Thin films of TiN were sputter-deposited onto Si and sapphire wafers with and without SiN buffer layers. The films were fabricated into RF coplanar waveguide resonators, and intern…