Speaker
Description
Spin qubits have seen much progress over recent years, proving to be an appealing candidate for scalable quantum computing with small footprints, electrical control, promising coherence times, and the industry-compatible silicon material platform. As advances are made in the spaces of control and scaling, addressing noise from various origins becomes increasingly pertinent. It has been shown that cosmic rays can cause bit flips and correlated errors in superconducting qubits [1]; however, similar effects in spin qubits have not been widely reported or studied in literature. To characterize the effects of ionizing radiation, we use a Cs-137 gamma source to irradiate Si/SiGe SLEDGE devices from HRL, obtained through the Qubits for Computing Foundry. We investigate the effects of ionizing radiation on the SETs using Coulomb-blockade peaks. We record significant drifts in peak positions that eventually saturate and persist after the source is removed. This behavior is attributed to filling of charge traps near the SETs after gamma rays Compton scatter and produce tracks of electrons and holes. A charge transport-based framework combining Monte Carlo simulations with Geant4/G4CMP, trapping dynamics, and a simple device model is developed to qualitatively explain this phenomenon. We note that discrete jumps in the peaks can also be observed, which we attribute to single radiation events. These jumps are also highly correlated between the two SETs. Preliminary measurements on the effects of gamma radiation on single exchange-only qubits are also performed, showing fidelity loss over time. These experiments should provide insights into the effects of environmental radiation on spin qubit devices.
[1] Li, X., Wang, J., Jiang, YY. et al. Cosmic-ray-induced correlated errors in superconducting qubit array. Nat Commun 16, 4677 (2025)
