  Annealing schedule control provides new opportunities to better understand
the manner and mechanisms by which putative quantum annealers operate. By
appropriately modifying the annealing schedule to include a pause (keeping the
Hamiltonian fixed) for a period of time, we show it is possible to more
directly probe the dissipative dynamics of the system at intermediate points
along the anneal and examine thermal relaxation rates, for example, by
observing the re-population of the ground state after the minimum spectral gap.
We provide a detailed comparison of experiments from a D-Wave device,
simulations of the quantum adiabatic master equation and a classical analogue
of quantum annealing, spin-vector Monte Carlo, and we observe qualitative
agreement, showing that the characteristic increase in success probability when
pausing is not a uniquely quantum phenomena. We find that the relaxation in our
system is dominated by a single time-scale, which allows us to give a simple
condition for when we can expect pausing to improve the time-to-solution, the
relevant metric for classical optimization. Finally, we also explore in
simulation the role of temperature whilst pausing as a means to better
distinguish quantum and classical models of quantum annealers.
