activity
20222026
most citedSystematic Improvements in Transmon Qubit Coherence Enabled by Niobium Surface Encapsulation

123 citations · 142 across the 10 of their papers we have counts for

collaborators

12 papers

quant-ph2026

Materials for Quantum Information Science: Roles in the Quantum Evolution 2.0

Thang Pham, Vsevolod Ivanov, Dominic P. Goronzy +4

Quantum information science is entering a second phase, the Quantum Evolution 2.0, in which the challenge has shifted from demonstrating coherent control of individual quantum stat…

quant-ph2026

Oxide-Nitride Heteroepitaxy for Low-Loss Dielectrics in Superconducting Quantum Circuits

David A. Garcia-Wetten, Mitchell J. Walker, Peter G. Lim +9

Superconducting qubits show great promise for the realization of fault-tolerant quantum computing, but lossy, amorphous dielectrics limit current technology. Identifying highly cry…

cond-mat.supr-con2026

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…

cond-mat.supr-con2026

Oxygen distribution and segregation at grain boundaries in Nb and Ta-encapsulated Nb thin films for superconducting qubits

Jaeyel Lee, Dieter Isheim, Zuhawn Sung +14

We report on atomic-scale analyses of oxygen distribution and segregation at grain boundaries (GBs) of Nb and Ta-encapsulated Nb (Ta/Nb) thin films for superconducting qubits using…

quant-ph2025

Comparison of Nb and Ta Pentoxide Loss Tangents for Superconducting Quantum Devices

D. P. Goronzy, W. W. Mah, P. G. Lim +14

Superconducting transmon qubits are commonly made with thin-film Nb wiring, but recent studies have shown increased performance with Ta wiring. In this work, we compare the resonat…

cond-mat.supr-con2025

Vortex-Controlled Quasiparticle Multiplication and Self-Growth Dynamics in Superconducting Resonators

Joong M. Park, Martin Mootz, Richard H. J. Kim +11

Even in the quantum limit, non-equilibrium quasiparticle (QP) populations induce QP poisoning that irreversibly relaxes the quantum state and significantly degrades the coherence o…

cond-mat.mtrl-sci2025

X-ray scattering investigation of hydride surface segregation in epitaxial Nb films

David A. Garcia-Wetten, Philip J. Ryan, Jong Woo Kim +4

Hydride precipitation in niobium-based, superconducting circuits is a damaging side-effect of hydrofluoric acid treatments used to clean and thin the Nb surface oxides and Si oxide…

quant-ph2025

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…

quant-ph2024★ 6 cited

Loss tangent fluctuations due to two-level systems in superconducting microwave resonators

André Vallières, Megan E. Russell, Xinyuan You +10

Superconducting microwave resonators are critical to quantum computing and sensing technologies. Additionally, they are common proxies for superconducting qubits when determining t…

cond-mat.mtrl-sci2024★ 6 cited

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…

quant-ph2023★ 123 cited

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…

cond-mat.supr-con2022★ 7 cited

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…