Radiation-induced secondary emissions in solid-state devices as a possible contribution to quasiparticle poisoning of superconducting circuits

This report estimates the potential for secondary emission processes induced by ionizing radiation to result in the generation of quasiparticles in superconducting circuits. These estimates are based on evaluation of data collected from a small superconducting detector and a fluorescence measurement of typical read-out circuit board materials. Specifically, we study cosmic ray muons interacting with substrate or mechanical support materials present within the vicinity of superconducting circuits. We evaluate the potential for secondary emission, such as scintillation and/or fluorescence, from these nearby materials to occur at sufficient energy (wavelength) and rate (photon flux) to ultimately lead to the breaking of superconducting Copper pairs (i.e., production of quasiparticles). This evaluation leads to a conclusion that material fluorescence in the vicinity of superconducting circuits is a potential contributor to undesirable elevated quasiparticle populations. A co-design approach evaluating superconducting circuit design and the material environment within the immediate vicinity of the circuit would prove beneficial for mitigating undesired environmentally-induced influences on superconducting device performance, such as in direct detection dark matter sensors or quantum computing bits (qubits).