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Radiation effects on superconducting devices, circuits, and qubits. Bridging classical electronics hardness and quantum coherence requirements

Gemma Rius

Published Apr 1, 2026• 1 citation
Publisher

Abstract

Radiation effects in electronic systems have been extensively studied within the context of classical micro- and nano-electronics, enabling reliable operation in space, nuclear, and other harsh environments through well-established concepts such as total ionizing dose, displacement damage, and single-event effects. Superconducting quantum technologies, however, operate in a fundamentally different regime, relying on macroscopic quantum coherence at millikelvin temperatures and energy scales many orders of magnitude smaller than those associated with ionizing radiation. Recent experiments have revealed that even rare radiation events, originating from cosmic rays or natural radioactivity, can generate quasiparticle bursts and non-equilibrium phonons, leading to decoherence and spatially correlated errors across multiple qubits. These phenomena challenge classical notions of radiation hardness and locality that underpin conventional mitigation strategies. This perspective bridges decades of radiation-effects knowledge from classical electronics with emerging insights from superconducting quantum devices, circuits, and qubits. The limitations of directly translating classical radiation-hardness concepts to quantum hardware and examining radiation interactions with superconducting materials and Josephson junctions are highlighted, and the distinct implications for quantum computing vs quantum sensing are discussed. Finally, critical gaps in testing, modeling, and multiscale simulation methodologies are identified, outlining directions toward radiation-aware quantum engineering that integrate materials science, device physics, and system-level design to enable robust, deployable quantum technologies.

DOI
10.1063/5.0319835

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Radiation effects in electronic systems have been extensively studied within the context of classical micro- and nano-electronics, enabling reliable operation in space, nuclear, and other harsh environments through well-established concepts such as total ionizing dose, displacement damage, and single-event effects. Superconducting quantum technologies, however, operate in a fundamentally different regime, relying on macroscopic quantum coherence at millikelvin temperatures and energy scales many orders of magnitude smaller than those associated with ionizing radiation. Recent experiments have revealed that even rare radiation events, originating from cosmic rays or natural radioactivity, can generate quasiparticle bursts and non-equilibrium phonons, leading to decoherence and spatially correlated errors across multiple qubits. These phenomena challenge classical notions of radiation hardness and locality that underpin conventional mitigation strategies. This perspective bridges decades of radiation-effects knowledge from classical electronics with emerging insights from superconducting quantum devices, circuits, and qubits. The limitations of directly translating classical radiation-hardness concepts to quantum hardware and examining radiation interactions with superconducting materials and Josephson junctions are highlighted, and the distinct implications for quantum computing vs quantum sensing are discussed. Finally, critical gaps in testing, modeling, and multiscale simulation methodologies are identified, outlining directions toward radiation-aware quantum engineering that integrate materials science, device physics, and system-level design to enable robust, deployable quantum technologies.
Abstract Ionizing radiation has been shown to reduce the performance of superconducting quantum circuits. In this report, we evaluate the expected contributions of different sources of ambient radioactivity for typical superconducting qubit experiment platforms. Our assessment of radioactivity inside a typical cryostat highlights the importance of selecting appropriate materials for the experiment components nearest to qubit devices, such as packaging and electrical interconnects. We present a shallow underground facility (30-meter water equivalent) to reduce the flux of cosmic rays and a lead shielded cryostat to abate the naturally occurring radiogenic gamma-ray flux in the laboratory environment. We predict that superconducting qubit devices operated in this facility could experience a reduced rate of correlated multi-qubit errors by a factor of approximately 20 relative to the rate in a typical above-ground, unshielded facility. Finally, we outline overall design improvements that would be required to further reduce the residual ionizing radiation rate, down to the limit of current generation direct detection dark matter experiments.
Ionizing radiation in the form of ααα, βββ, γγγ, and additional high-energy particles can induce decoherence via phonon and quasiparticle poisoning in superconducting qubits. Recent studies have explored this effect using cosmic rays or controlled radioactive sources held in the proximity of a qubit package, and have concluded that reductions in such ``external'' environmental radiation may benefit stable operation of qubit devices. However, the effect of long-lived, unstable daughters of 222^{222}222Rn that ``plate out'' directly on device and packaging surfaces has not been as extensively explored. This plate-out process, well-known to the dark matter direct detection field, occurs throughout the fabrication and testing lifecycle of a device and (separately) its packaging, and produces a local source of ααα-decays which can remain active for decades. As this scales with chip area, understanding and managing this source of ionizing radiation is relevant for successfully scaling quantum computing architectures to larger numbers of qubits in a radiation-robust way. We present a setup capable of accelerating and enhancing radon daughter plateout by a factor of 7×1047\times10^47×104 over ambient, in order to study, \textit{in situ}, the impact of these events on superconducting qubits. We also provide outlook on the potential impact of this source of ionizing radiation on current and future qubit arrays.
Impacts from high-energy particles cause correlated errors in superconducting qubits by increasing the quasiparticle density in the vicinity of the Josephson junctions (JJs). Such errors are particularly harmful as they cannot be easily remedied via conventional error correcting codes. Recent experiments reduced correlated errors by making the difference in superconducting gap energy across the JJ larger than the qubit transition energy. In this work, we assess gap engineering near the JJ (δΔJJδΔ_{\mathrm{JJ}}δΔJJ​) and the capacitor/ground-plane (δΔM1δΔ_{\mathrm{M1}}δΔM1​) by exposing arrays of transmon qubits to two sources of radiation. For ααα-particles from an 241^{241}241Am source, we observe T1T_1T1​ errors correlated in space and time, supporting a hypothesis that hadronic cosmic rays are a major contributor to the 10−1010^{-10}10−10 error floor observed in Ref. 1. For electrons from a pulsed linear accelerator, we observe temporally correlated T1T_1T1​ and T2T_2T2​ errors, this measurement is insensitive to spatial correlations. We observe that the severity of correlated T1T_1T1​ errors is reduced for qubit arrays with a greater degree of gap engineering at the JJ. For both T1T_1T1​ and T2T_2T2​ errors, the recovery time is hastened by an increased δΔM1δΔ_{\mathrm{M1}}δΔM1​, which we attribute to the trapping of quasiparticles into the capacitor/ground-plane. We construct a model of quasiparticle dynamics that qualitatively agrees with our observations. This work reinforces the multifaceted influence of radiation on superconducting qubits and provides strategies for improving radiation resilience.
Abstract 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 measure levels of radioactivity present in a typical laboratory environment (from muons, neutrons, and γ\gamma γ γ -rays emitted by naturally occurring radioactive isotopes) and in the most commonly used materials for the assembly and operation of state-of-the-art superconducting qubits. We present a GEANT-4 based simulation to predict the rate of impacts and the amount of energy released in a qubit chip from each of the mentioned sources. We finally propose mitigation strategies for the operation of next-generation qubits in a radio-pure environment.
Environmental radioactivity and cosmic-rays have recently been identified as a source of decoherence in super-conducting quantum bits (qubits). In particular, the absorption of cosmic-ray muons and gamma rays emitted by naturally occurring radioactive isotopes in the qubit substrate leads to correlated errors in superconducting quantum processors, posing significant challenges to quantum error correction. To enable quantum computing to scale, it is therefore necessary the devel-opment of mitigation strategies to prevent, or keep under control, error bursts due to particle impacts in the chip. While most environmental radioactive sources can be effectively suppressed using dedicated shielding, cosmic-ray muons, with their high penetration capability, can only be mitigated by moving the entire facility in a deep underground laboratory. This work explores the potential for developing a novel class of quantum processors equipped with an active veto system to protect superconducting-based quantum computers from the detrimental effects of atmospheric muons. Such a device would enable the identification of an atmospheric muon interaction within the processor and veto all operations performed during the occurrence of such an interaction. By demonstrating high detection efficiency and negligible dead time, we aim to establish that the future of quantum processors can be envisioned in above-around facilities.
The superconducting qubit quantum computer is one of the most promising quantum computing architectures for large-scale integration due to its maturity and close proximity to the well-established semiconductor manufacturing infrastructure. From an education perspective, it also bridges classical microwave electronics and quantum electrodynamics. In this paper, we will review the basics of quantum computers, superconductivity, and Josephson junctions. We then introduce important technologies and concepts related to DiVincenzo's criteria, which are the necessary conditions for the superconducting qubits to work as a useful quantum computer. Firstly, we will discuss various types of superconducting qubits formed with Josephson junctions, from which we will understand the trade-off across multiple design parameters, including their noise immunity. Secondly, we will discuss different schemes to achieve entanglement gate operations, which are a major bottleneck in achieving more efficient fault-tolerant quantum computing. Thirdly, we will review readout engineering, including the implementations of the Purcell filters and quantum-limited amplifiers. Finally, we will discuss the nature and review the studies of two-level system defects, which are currently the limiting factor of qubit coherence time. DiVincenzo's criteria are only the necessary conditions for a technology to be eligible for quantum computing. To have a useful quantum computer, large-scale integration is required. We will review proposals and developments for the large-scale integration of superconducting qubit devices. By comparing with the application of electronic design automation (EDA) in semiconductors, we will also review the use of EDA in superconducting qubit quantum computer design, which is necessary for its large-scale integration.