123 citations · 182 across the 12 of their papers we have counts for
13 papers
Magnetic flux distribution, quasiparticle spectroscopy, and quality factors in Nb films for superconducting qubits
Amlan Datta, Bicky S. Moirangthem, Kamal R. Joshi +6
Niobium is a practical material platform for superconducting microwave circuits; however, device-level performance can vary significantly depending on film growth and processing co…
Quasiparticle spectroscopy in tantalum films with different Ta/sapphire interfaces
Bicky S. Moirangthem, Kamal R. Joshi, Anthony P. Mcfadden +8
One of the crucial aspects of current research in quantum information science is the identification and control of loss mechanisms in superconducting circuits. Although microwave m…
Magneto-optical study of Nb thin films for superconducting qubits
Amlan Datta, Kamal R. Joshi, Sunil Ghimire +7
Among the recognized sources of decoherence in superconducting qubits, the spatial inhomogeneity of the superconducting state and the possible presence of magnetic-flux vortices re…
Effect of metal encapsulation on bulk superconducting properties of niobium thin films used in qubits
Amlan Datta, Kamal R. Joshi, Sunil Ghimire +18
Niobium metal occupies nearly 100\% of the volume of a typical 2D transmon device. While the aluminum Josephson junction is of utmost importance, maintaining quantum coherence acro…
Identifying Materials-Level Sources of Performance Variation in Superconducting Transmon Qubits
Akshay A. Murthy, Mustafa Bal, Michael J. Bedzyk +46
The Superconducting Materials and Systems (SQMS) Center, a DOE National Quantum Information Science Research Center, has conducted a comprehensive and coordinated study using super…
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…
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…
Understanding the Mechanism of the Performance Improvement in Nitrogen-doped Niobium Superconducting Radio Frequency Cavity
Xiaotian Fang, Jin-Su Oh, Matt Kramer +4
Niobium superconducting radiofrequency cavities enable applications in modern accelerators and quantum computers. However, the surface resistance significantly deteriorates the cav…
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…
Visualizing heterogeneous dipole fields by terahertz light coupling in individual nano-junctions used in transmon qubits
R. H. J. Kim, J. M. Park, S. Haeuser +12
The fundamental challenge underlying superconducting quantum computing is to characterize heterogeneity and disorder in the underlying quantum circuits. These nonuniform distributi…
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…