Barrier crossing in a viscoelastic bath

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.