Stochastic resonance in colloidal systems

We investigate the dynamical properties of a colloidal particle in a double-well potential which is periodically modulated in time. In case of the modulation corresponding to a tilt of the potential (asymmetric modulation), stochastic resonance is observed when the modulation frequency nu(Omega) matches one half of the Kramers frequency of the unperturbed potential. In contrast, when only the potential barrier height is modulated (symmetric modulation), no synchronization between the modulation and the particle dynamics is observed as demonstrated by the lack of a peak in the power spectrum at nu(Omega).