  As spin-based quantum processors grow in size and complexity, maintaining
high fidelities and minimizing crosstalk will be essential for the successful
implementation of quantum algorithms and error-correction protocols. In
particular, recent experiments have highlighted pernicious transient qubit
frequency shifts associated with microwave qubit driving. Workarounds for small
devices, including prepulsing with an off-resonant microwave burst to bring a
device to a steady-state, wait times prior to measurement, and qubit-specific
calibrations all bode ill for device scalability. Here, we make substantial
progress in understanding and overcoming this effect. We report a surprising
non-monotonic relation between mixing chamber temperature and spin Larmor
frequency which is consistent with observed frequency shifts induced by
microwave and baseband control signals. We find that purposefully operating the
device at 200 mK greatly suppresses the adverse heating effect while not
compromising qubit coherence or single-qubit fidelity benchmarks. Furthermore,
systematic non-Markovian crosstalk is greatly reduced. Our results provide a
straightforward means of improving the quality of multi-spin control while
simplifying calibration procedures for future spin-based quantum processors.
