Energy Deposition in Superconducting Quantum Devices from Different Cosmic-Ray Components

Naturally occurring background radiation such as cosmic rays can cause correlated decoherence events in superconducting qubits and disrupt error correction in quantum computers. While the primary cosmic rays entering Earth's atmosphere are mostly protons or other ionized light nuclei, interactions with air molecules lead to showers of secondary cosmic rays that consist of muons, electrons, positrons, protons, neutrons, and gamma rays. In this work, the cosmic-ray composition and energy spectra at sea level from the cosmic-ray shower generator CRY were entered as inputs to GEANT4 simulations of quantum sensor arrays in a dilution refrigerator surrounded by a laboratory overburden. The spectra of energy deposited in the quantum sensors from the different cosmic-ray constituents were compared. Furthermore, the G4CMP add-on to GEANT4 was utilized to propagate the electrons, holes, and phonons produced by the cosmic-ray energy deposition to determine the energy ultimately deposited in the qubits from the various cosmic-ray particles.