123 citations · 288 across the 19 of their papers we have counts for
19 papers
Enhanced Superconducting Qubit Performance Through Ammonium Fluoride Etch
Cameron J. Kopas, Dominic P. Goronzy, Thang Pham +19
The performance of superconducting qubits is often limited by dissipation and two-level systems (TLS) losses. The dominant sources of these losses are believed to originate from am…
Precision frequency tuning of tunable transmon qubits using alternating-bias assisted annealing
Xiqiao Wang, Joel Howard, Eyob A. Sete +13
Superconducting quantum processors are one of the leading platforms for realizing scalable fault-tolerant quantum computation (FTQC). The recent demonstration of post-fabrication t…
Transport signatures of phase fluctuations in superconducting qubits
Maxwell Wisne, Yanpei Deng, Hilal Cansizoglu +3
Josephson junctions supply the nonlinear inductance element in superconducting qubits. In the widely used transmon configuration, where the junction is shunted by a large capacitor…
Formation and Microwave Losses of Hydrides in Superconducting Niobium Thin Films Resulting from Fluoride Chemical Processing
Carlos G. Torres-Castanedo, Dominic P. Goronzy, Thang Pham +18
Superconducting Nb thin films have recently attracted significant attention due to their utility for quantum information technologies. In the processing of Nb thin films, fluoride-…
Alternating Bias Assisted Annealing of Amorphous Oxide Tunnel Junctions
David P. Pappas, Mark Field, Cameron Kopas +10
We demonstrate a transformational technique for controllably tuning the electrical properties of fabricated thermally oxidized amorphous aluminum-oxide tunnel junctions. Using conv…
Quasiparticle spectroscopy in technologically-relevant niobium using London penetration depth measurements
Sunil Ghimire, Kamal R. Joshi, Amlan Datta +10
London penetration depth was measured in niobium foils, thin films, single crystals, and superconducting radio-frequency (SRF) cavity pieces cut out from different places. The low-…
Systematic Improvements in Transmon Qubit Coherence Enabled by Niobium Surface Encapsulation
Mustafa Bal, Akshay A. Murthy, Shaojiang Zhu +37
We present a novel transmon qubit fabrication technique that yields systematic improvements in T relaxation times. We fabricate devices using an encapsulation strategy that inv…
Disentangling the sources of ionizing radiation in superconducting qubits
L. Cardani, I. Colantoni, A. Cruciani +27
Radioactivity was recently discovered as a source of decoherence and correlated errors for the real-world implementation of superconducting quantum processors. In this work, we mea…
Characterization of Nb films for superconducting qubits using phase boundary measurements
Kevin M. Ryan, Carlos G. Torres-Castanedo, Dominic P. Goronzy +8
Continued advances in superconducting qubit performance require more detailed understandings of the many sources of decoherence. Within these devices, two-level systems arise due t…
Quasiparticle spectroscopy, transport, and magnetic properties of Nb films used in superconducting transmon qubits
Kamal R. Joshi, Sunil Ghimire, Makariy A. Tanatar +10
Niobium thin films on silicon substrate used in the fabrication of superconducting qubits have been characterized using scanning and transmission electron microscopy, electrical tr…
Anisotropic superconductivity of niobium based on its response to non-magnetic disorder
Makariy A. Tanatar, Daniele Torsello, Kamal R. Joshi +8
Niobium is one of the most studied superconductors, both theoretically and experimentally. It is tremendously important for applications, and it has the highest superconducting tra…
Contactless Excitation of Acoustic Resonance in Insulating Wafers
Gan Zhai, Yizhou Xin, Cameron J. Kopas +7
Contactless excitation and detection of high harmonic acoustic overtones in a thin insulator single crystal are described using radio frequency spectroscopy techniques. Single crys…
Simple coplanar waveguide resonator mask targeting metal-substrate interface
Cameron J. Kopas, Ella Lachman, Corey Rae H. McRae +4
This white paper presents a single-layer mask, found at https://github.com/Boulder-Cryogenic-Quantum-Testbed/simple-resonator-mask. It is designed for fabrication of superconductin…
Multi-modal electron microscopy study on decoherence sources and their stability in Nb based superconducting qubit
Jin-Su Oh, Xiaotian Fang, Tae-Hoon Kim +14
Niobium is commonly used for superconducting quantum systems as readout resonators, capacitors, and interconnects. The coherence time of the superconducting qubits is mainly limite…
Developing a Chemical and Structural Understanding of the Surface Oxide in a Niobium Superconducting Qubit
Akshay A. Murthy, Paul Masih Das, Stephanie M. Ribet +11
Superconducting thin films of niobium have been extensively employed in transmon qubit architectures. Although these architectures have demonstrated remarkable improvements in rece…
TOF-SIMS Analysis of Decoherence Sources in Nb Superconducting Resonators
Akshay A. Murthy, Jae-Yel Lee, Cameron Kopas +6
Superconducting qubits have emerged as a potentially foundational platform technology for addressing complex computational problems deemed intractable with classical computing. Des…
Ge thin-films with tantalum diffusion-barriers for use in Nb-based superconductor technology
C. Kopas, S. Zhang, J. Gonzales +4
Germanium thin films are an excellent candidate for use as a low-loss dielectric in superconducting microwave resonators, a low-loss inter-layer metal wiring dielectric, and passiv…
Characterization of the Chemical and Electrical Properties of Defects at the Niobium-Silicon Interface
Cameron Kopas, Madhu Krishna Murthy, Christopher Gregory +4
The nature and concentration of defects near niobium-silicon interfaces prepared with different silicon surface treatments were characterized using current-voltage (I-V), deep leve…
Low microwave loss in deposited Si and Ge thin-film dielectrics at single-photon power and low temperatures
Cameron J. Kopas, Justin Gonzales, Shengke Zhang +5
Our study shows that deposited Ge and Si dielectric thin-films can exhibit low microwave losses at near single-photon powers and sub-Kelvin temperatures (40 mK). This low…