Thermally activated barrier crossing and stochastic resonance of a flexible polymer chain in a piecewise linear bistable potential

We study the stochastic resonance of a flexible polymer chain crossing over a piecewise linear bistable potential. The dependence of signal to noise ratio SNR on noise intensity D, coupling constant k, and polymer length N is studied via two-state approximation. We find that the response of signal to the background noise strength is significant at optimum values of D-opt, k(opt), and N-opt which suggests a means of manipulating proteins or vesicles. Furthermore, the thermally activated barrier crossing rate r(k) for the flexible polymer chain is studied. We find that the crossing rate r(k) exhibits an optimal value at an optimal coupling constant k(opt); k(opt) decreases with N. As the chain length N increases, the escape rate for the center of mass r(k) monotonously decreases. On the other hand, the crossing rate for the portion of polymer segment r(s) increases and saturates to a constant rate as N steps up.