Though stochastic resonance was usually shown to occur in bistable systems whereas ratchet effect necessarily occurs in periodic potential systems, it was conjectured [Nature 369, 181 (1994), ibid 369,271 (1994)] that these two non-equilibrium phenomena have some commonalities. Since for proper comparison both the phenomena need to occur in the same system, in the present work, we show first that stochastic resonance too occurs in periodic potential system, and then, in addition show that the ratchet effect also occurs in the same parameter space of the system where stochastic resonance occurs. In order to obtain ratchet effect we consider periodic non-uniformity of the friction coefficient of the medium to provide the necessary asymmetry in the symmetrically driven sinusoidal potential system. However, the temperature at which stochastic resonance occurs is different from the temperature at which ratchet current peaks.
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