# Saving superconducting quantum processors from qubit decay and correlated errors generated by gamma and cosmic rays

**Authors:** John M. Martinis  
**arXiv:** [2012.06137](https://arxiv.org/abs/2012.06137)  
**Date:** 2020-12-11  
**Summary page:** https://www.summarizepaper.com/fr/arxiv-id/2012.06137v3/

## Abstract

Error-corrected quantum computers can only work if errors are small and uncorrelated. Here I show how cosmic rays or stray background radiation affects superconducting qubits by modeling the phonon to electron/quasiparticle down-conversion physics. For present designs, the model predicts about 57\% of the radiation energy breaks Cooper pairs into quasiparticles, which then vigorously suppress the qubit energy relaxation time ($T_1 \sim$ 160 ns) over a large area (cm) and for a long time (ms). Such large and correlated decay kills error correction. Using this quantitative model, I show how this energy can be channeled away from the qubit so that this error mechanism can be reduced by many orders of magnitude. I also comment on how this affects other solid-state qubits.