  Leakage from the computational subspace is a damaging source of noise that
degrades the performance of most qubit types. Unlike other types of noise,
leakage cannot be overcome by standard quantum error correction techniques and
requires dedicated leakage reduction units. In this work, we study the effects
of leakage mobility between superconducting qubits on the performance of a
quantum stability experiment, which is a benchmark for fault-tolerant logical
computation. Using the Fujitsu Quantum Simulator, we perform full
density-matrix simulations of stability experiments implemented on the surface
code. We observe improved performance with increased mobility, suggesting
leakage mobility can itself act as a leakage reduction unit by naturally moving
leakage from data to auxiliary qubits, where it is removed upon reset. We
compare the performance of standard error-correction circuits with "patch
wiggling", a specific leakage reduction technique where data and auxiliary
qubits alternate their roles in each round of error correction. We observe that
patch wiggling becomes inefficient with increased leakage mobility, in contrast
to the improved performance of standard circuits. These observations suggest
that the damage of leakage can be overcome by stimulating leakage mobility
between qubits without the need for a dedicated leakage reduction unit.
