Computed models of natural radiation backgrounds in qubits and superconducting detectors

Published

December 9, 2024

Author(s)

Joseph Fowler, Ian Fogarty Florang, Nathan Nakamura, Daniel Swetz, Paul Szypryt, Joel Ullom

Abstract

Naturally occurring radiation backgrounds cause correlated decoherence events in superconducting qubits. These backgrounds include gamma rays produced by terrestrial radioisotopes and cosmic rays. We use the particle-transport code Geant4 and the PARMA summary of the cosmic-ray spectrum to model both sources of natural radiation and to study their effects in the typical substrates used in superconducting electronics. We focus especially on three rates that summarize radiation's effect on substrates. We give analytic expressions for these rates, and how they depend upon parameters including laboratory elevation, substrate material, shielding materials, and wafer area and thickness. The modeled rates and the distribution of event energies are consistent with our earlier measurement of radiation backgrounds using a silicon thermal kinetic-inductance detector.

Proceedings Title

IEEE Transactions on Applied Superconductivity

Volume

35

Issue

5

Conference Dates

September 2-6, 2024

Conference Location

Salt Lake City, UT, US

Conference Title

Applied Superconductivity 2024

Pub Type

Conferences

Download Paper

https://doi.org/10.1109/TASC.2024.3512523

Local Download

Keywords

Superconducting devices, qubits, interactions of radiation with superconducting circuits

Citation

Fowler, J. , Fogarty Florang, I. , Nakamura, N. , Swetz, D. , Szypryt, P. and Ullom, J. (2024), Computed models of natural radiation backgrounds in qubits and superconducting detectors, IEEE Transactions on Applied Superconductivity, Salt Lake City, UT, US, [online], https://doi.org/10.1109/TASC.2024.3512523, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=958816 (Accessed July 3, 2026)

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