  The noise-flatness-induced hypersensitive transport of overdamped Brownian
particles in a tilted ratchet system driven by multiplicative nonequilibrium
three-level Markovian noise and additive white noise is considered. At low
temperatures the enhancement of current is very sensitive to the applied small
static tilting force. It is established that the enhancement of mobility
depends non-monotonically on the parameters (flatness, correlation time) of
multiplicative noise. The optimal values of noise parameters maximizing the
mobility are found.
