Quantitative characterization of superconducting qubits as particle detectors
Abstract
Ionizing radiation is a major source of correlated errors in superconducting quantum processors, yet the mechanisms responsible for the qubit response to particle interactions remain only partially understood. In this work, we operate superconducting qubits as particle detectors while simultaneously monitoring the deposited energy with an independent semiconductor cryogenic sensor. This complementary measurement provides an absolute determination of the particle interaction rate in the chip, enabling the first direct measurement of the detection efficiency of superconducting qubits exposed to environmental radiation. We measure individual qubit detection efficiencies of about 30-40%, increasing to approximately 50% when combining the response of two qubits. Under the conservative assumption that the efficiency loss is entirely determined by a finite detection threshold, we derive an upper limit on the effective energy threshold of the detector of 70±20 (stat)±30 (syst) keV. Measurements with radioactive sources producing different deposited-energy spectra further show that the detection efficiency decreases for lower-energy interactions. We further investigate the origin of the qubit response by injecting controlled thermal pulses with a resistive heater. Although these pulses deposit energies comparable to those released by particle interactions, they do not reproduce the radiation-induced signatures, demonstrating that the qubit response to radiation cannot be explained by a transient increase in substrate temperature alone. Our results establish an experimental framework for quantitatively connecting particle energy deposition to radiation-induced responses in superconducting quantum circuits.
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BibTeX
@misc{dominicis2026quantitative,
title = {{Quantitative characterization of superconducting qubits as particle detectors}},
author = {Francesco De Dominicis and Raja Yasir Mehmood Khan and Dounia L Helis and Ambra Mariani and Letizia Tirabasso and Alberto Ressa and Mustafa Bal and Fabio Bellini and Camilla Bonomo and Nicola Casali and Gianluigi Catelani and Ivan Colantoni and Francesco Crisa and Angelo Cruciani and Sabrina Garattoni and Luca Gironi and Andrea Melchiorre and Lorenzo Pagnanini and Valerio Pettinacci and Stefano Pirro and Andrei Puiu and Tanay Roy and Shaojiang Zhu and Anna Grassellino and Laura Cardani},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.35850},
eprint = {2609.35850},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.35850},
}
RIS
TY - UNPB
TI - Quantitative characterization of superconducting qubits as particle detectors
AU - Francesco De Dominicis
AU - Raja Yasir Mehmood Khan
AU - Dounia L Helis
AU - Ambra Mariani
AU - Letizia Tirabasso
AU - Alberto Ressa
AU - Mustafa Bal
AU - Fabio Bellini
AU - Camilla Bonomo
AU - Nicola Casali
AU - Gianluigi Catelani
AU - Ivan Colantoni
AU - Francesco Crisa
AU - Angelo Cruciani
AU - Sabrina Garattoni
AU - Luca Gironi
AU - Andrea Melchiorre
AU - Lorenzo Pagnanini
AU - Valerio Pettinacci
AU - Stefano Pirro
AU - Andrei Puiu
AU - Tanay Roy
AU - Shaojiang Zhu
AU - Anna Grassellino
AU - Laura Cardani
PY - 2026
DA - 2026/09/25
PB - arXiv
DO - 10.48550/arxiv.2609.35850
UR - https://arxiv.org/abs/2609.35850
AB - Ionizing radiation is a major source of correlated errors in superconducting quantum processors, yet the mechanisms responsible for the qubit response to particle interactions remain only partially understood. In this work, we operate superconducting qubits as particle detectors while simultaneously monitoring the deposited energy with an independent semiconductor cryogenic sensor. This complementary measurement provides an absolute determination of the particle interaction rate in the chip, enabling the first direct measurement of the detection efficiency of superconducting qubits exposed to environmental radiation. We measure individual qubit detection efficiencies of about 30-40%, increasing to approximately 50% when combining the response of two qubits. Under the conservative assumption that the efficiency loss is entirely determined by a finite detection threshold, we derive an upper limit on the effective energy threshold of the detector of 70±20 (stat)±30 (syst) keV. Measurements with radioactive sources producing different deposited-energy spectra further show that the detection efficiency decreases for lower-energy interactions. We further investigate the origin of the qubit response by injecting controlled thermal pulses with a resistive heater. Although these pulses deposit energies comparable to those released by particle interactions, they do not reproduce the radiation-induced signatures, demonstrating that the qubit response to radiation cannot be explained by a transient increase in substrate temperature alone. Our results establish an experimental framework for quantitatively connecting particle energy deposition to radiation-induced responses in superconducting quantum circuits.
ER -