  Fault-tolerant quantum computation relies on the assumption of
time-invariant, sufficiently low physical error rates. However, current
superconducting quantum computers suffer from frequent disruptive noise events,
including cosmic ray impacts and shifting two-level system defects. Several
methods have been proposed to mitigate these issues in software, but they add
large overheads in terms of physical qubit count, as it is difficult to
preserve logical information through burst error events. We focus on mitigating
multi-qubit burst errors in magic state factories, which are expected to
comprise up to 95% of the space cost of future quantum programs. Our key
insight is that magic state factories do not need to preserve logical
information over time; once we detect an increase in local physical error
rates, we can simply turn off parts of the factory that are affected, re-map
the factory to the new chip geometry, and continue operating. This is much more
efficient than previous more general methods, and is resilient even under many
simultaneous impact events. Using precise physical noise models, we show an
efficient ray detection method and evaluate our strategy in different noise
regimes. Compared to existing baselines, we find reductions in ray-induced
overheads by several orders of magnitude, reducing total qubitcycle cost by
geomean 6.5x to 13.9x depending on the noise model. This work reduces the
burden on hardware by providing low-overhead software mitigation of these
errors.
