  We investigate the hopping dynamics of a colloidal particle across a
potential barrier and within a viscoelastic, i.e., non-Markovian bath, and
report two clearly separated time scales in the corresponding waiting time
distributions. While the longer time scale exponentially depends on the barrier
height, the shorter one is similar to the relaxation time of the fluid. This
short time scale is a signature of the storage and release of elastic energy
inside the bath, that strongly increases the hopping rate. Our results are in
excellent agreement with numerical simulations of a simple Maxwell model.
