  We propose a method to assist fault mitigation in quantum computation through
the use of sensors co-located near physical qubits. Specifically, we consider
using transition edge sensors co-located on silicon substrates hosting
superconducting qubits to monitor for energy injection from ionizing radiation,
which has been demonstrated to increase decoherence in transmon qubits. We
generalize from these two physical device concepts and explore the potential
advantages of co-located sensors to assist fault mitigation in quantum
computation. In the simplest scheme, co-located sensors beneficially assist
rejection of calculations potentially affected by environmental disturbances.
Investigating the potential computational advantage further required
development of an extension to the standard formulation of quantum error
correction. In a specific case of the standard three-qubit, bit-flip quantum
error correction code, we show that given a 20% overall error probability per
qubit, approximately 90% of repeated calculation attempts are correctable.
However, when sensor-detectable errors account for 45% of overall error
probability, the use of co-located sensors uniquely associated with independent
qubits boosts the fraction of correct final-state calculations to 96%, at the
cost of rejecting 7% of repeated calculation attempts.
