  Ion traps are promising architectures for implementing scalable quantum
computing, but they suffer from excessive "anomalous" heating that prevents
their full potential from being realized. This heating, which is orders of
magnitude larger than that expected from Johnson-Nyquist noise, results in ion
motion that leads to decoherence and reduced fidelity in quantum logic gates.
The exact origin of anomalous heating is an open question, but experiments
point to adsorbates on trap electrodes as a likely source. Many different
models of anomalous heating have been proposed, but these models have yet to
pinpoint the atomistic origin of the experimentally-observed $1/\omega$
electric field noise scaling observed in ion traps at frequencies between
0.1-10 MHz. In this work, we perform the first computational study of the ion
trap electric field noise produced by the motions of multiple monolayers of
adsorbates described by first principles potentials. In so doing, we show that
correlated adsorbate motions play a definitive role in producing $1/\omega$
noise and identify candidate collective adsorbate motions, including
translational and rotational motions of adsorbate patches and multilayer
exchanges, that give rise to $1/\omega$ scaling at the MHz frequencies
typically employed in ion traps. These results demonstrate that multi-adsorbate
systems, even simple ones, can give rise to a set of activated motions that can
produce the $1/\omega$ noise observed in ion traps and that collective, rather
than individual, adsorbate motions are much more likely to give rise to
low-frequency heating.
