Cryogenic Muon Tagging System with Kinetic Inductance Detectors Monitors Radiation for Quantum Processors
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Ionizing radiation poses a significant threat to the reliable operation of advanced superconducting quantum processors, and atmospheric muons, with their exceptional energy and penetrating power, represent a particularly challenging source of error. To address this issue, Ambra Mariani, Laura Cardani, Mustafa Bal, and colleagues at their respective institutions have developed a cryogenic muon-tagging system based on Kinetic Inductance Detectors. This innovative system actively monitors real-time muon flux, offering a crucial step towards developing effective error-correction strategies and protecting delicate quantum states.
The team’s prototype, operating at extremely low temperatures, achieves a remarkable 90% muon-tagging efficiency with negligible delay, and experimental results closely match detailed computer simulations, demonstrating the feasibility of integrating this technology with multi-qubit chips to mitigate the impact of cosmic radiation in future quantum computers.
Cosmic Ray Errors in Superconducting Qubits Superconducting qubits, the building blocks of promising quantum computers, are exceptionally sensitive to environmental noise, which limits their ability to reliably process information. A major source of this noise is ionizing radiation, including cosmic rays and natural radioactivity, that deposits energy into the qubit materials and creates errors. As quantum computers grow in size, the impact of radiation becomes increasingly significant, necessitating effective mitigation techniques to ensure stable and reliable operation.
Muon Tagging System for Superconducting Qubits Scientists have engineered a cryogenic muon-tagging system to monitor atmospheric muons, high-energy particles that represent a significant source of error in superconducting quantum processors.
Detailed Monte Carlo simulations, employing the Geant4 toolkit, were used to optimize the prototype design, predicting both muon-tagging efficiency and the rate of accidental coincidences caused by ambient gamma rays. Researchers meticulously modeled particle interactions within the detector system, incorporating both atmospheric muons and environmental gamma rays. Established sea-level measurements reproduced muon spectra and angular distributions, while direct laboratory measurements using a portable scintillator determined the gamma ray flux. Particles were propagated through a full geometric model of the system, recording energy deposition in each silicon wafer to calculate interaction rates. Experiments measured a muon-induced coincidence rate of (192 ±9) × 10 -3 events/s between the top and bottom detectors, closely aligning with the predictions from the Geant4 simulations. The system achieves a muon-tagging efficiency of approximately 90% with negligible dead time, demonstrating its ability to reliably identify muon events. Detailed analysis assessed the impact of accidental coincidences caused by environmental gamma rays, estimating a total accidental coincidence rate of (3. 2) × 10 -3 events/s within a 340μs coincidence window. Calculations reveal that even with a 25ms veto gate, the fractional dead time due to gamma-induced coincidences remains below 0. 05%, confirming that ambient radiation does not significantly limit the system’s live time performance. This validation confirms the feasibility of integrating the muon-tagging system with multi-qubit chips to veto or correct errors caused by muon interactions in real time.
Muon Tagging System Protects Quantum Processors Scientists have achieved a breakthrough in mitigating the effects of ionizing radiation on superconducting quantum processors, a growing limitation to fault-tolerant operation. This system actively identifies muons before they can disrupt quantum computations, paving the way for real-time error correction or vetoing. The core of the system is a vertical stack of three detectors, with the top and bottom layers functioning as the muon-tagging system and a central detector serving as a proxy for the quantum chip during testing. Each detector incorporates a KID, a superconducting resonator fabricated on a 525-μm-thick, high-resistivity silicon substrate. These KIDs, featuring a meandered inductor approximately 6cm long and 62. 5μm wide, are designed to detect the energy deposited as a muon traverses the detector. Experiments revealed a muon-induced coincidence rate of (192 ±9) × 10 -3 events per second, demonstrating excellent agreement with predictions from detailed Monte Carlo simulations based on Geant4. The prototype achieves a muon-tagging efficiency of approximately 90% with negligible dead time, meaning the system can identify nearly all passing muons without significant delay. Researchers demonstrated the feasibility of operating a muon-tagging system at millikelvin temperatures, a critical requirement for compatibility with superconducting qubits. These results open the path toward integrating the system with multi-qubit chips to actively identify and potentially correct or reject muon-induced errors, representing a significant step toward robust, scalable quantum computing platforms operating above ground.
Muon Tagging Validates Quantum Error Mitigation This research demonstrates the successful development and initial operation of a cryogenic muon-tagging system designed for use with superconducting quantum processors. The system, based on kinetic inductance detectors, reliably identifies muons, particles from cosmic radiation that can induce errors in quantum computations, at millikelvin temperatures. Measurements of muon-induced coincidence rates closely matched predictions from detailed Monte Carlo simulations, confirming a muon-tagging efficiency of approximately 90% with negligible dead time. These results establish the feasibility of integrating a highly efficient, low-latency muon-tagging system into above-ground superconducting quantum processors.
The team plans to concentrate future work on coupling the system to multi-qubit chips and developing strategies to either veto or correct errors caused by muon strikes. Further optimization of detector geometries and materials also promises to enhance detection efficiency, ultimately contributing to more reliable quantum computation. 👉 More information 🗞 A Cryogenic Muon Tagging System Based on Kinetic Inductance Detectors for Superconducting Quantum Processors 🧠 ArXiv: https://arxiv.org/abs/2512.10679 Tags: