Coherent stochastic resonance in a sextic double-well potential

We study the response of a stochastic system described by the one-dimensional Fokker-Planck equation with a sextic double-well potential U-6(x) = (-c(4)x(4) + c(6)x(6)) to a weak sinusoidal periodic signal. Two types of boundary conditions have been investigated: (i) absorbing boundary conditions, and (ii) natural boundary conditions. The unperturbed propagators are calculated by the eigenfunction-expansion method. We find that for case (i), the mean survival time shows the coherent stochastic resonance, and for case (ii), the signal-to-noise ratio exhibits the stochastic resonance. The results are compared with those of the bistable quartic double-well potential U-4(x) = (-1/2x(2) + 1/4x(4)). (C) 2002 Elsevier Science B.V. All rights reserved.