Understanding the Contributions of Terrestrial Radiation Sources to Error Rates in Quantum Devices

Quantum computing (QC), despite being a highly promising computational paradigm, suffers from an incredibly high radiation sensitivity. Recent discoveries highlighted that the impact of a particle in the quantum bit (qubit) is tens of thousands of times more likely to induce a fault compared to traditional CMOS devices. Moreover, the deposited charge quickly diffuses in the substrate affecting multiple qubits, inducing faults that can persist for hundreds of seconds. In this article, we aim to better understand the effect of different radiation sources and mechanisms of energy propagation on quantum devices. We present data from the simulation of more than 18 billion particle interactions. Through GEANT4 simulations, we compare the effect of neutrons, alpha particles, muons, and gamma rays in a quantum device. We combine nonequilibrium generation probability with natural flux to identify the most harmful radiation source for qubits. We found that muons are, by far, the more likely cause of faults in qubits. Moreover, through G4CMP simulations, we track the energy propagation in the substrate. We show that even particle hits far from the qubit can lead to energy transmission to the superconductor, also pointing out that this mechanism is 1000 times more likely than a direct energy deposition on the qubit. In addition, we show that the time persistency of secondary particles in the substrate is in the order of $100~\mu $ s. Finally, we look at particle impacts on a four-qubit device to show that with a common layout, multiple-qubit are likely to be corrupted.