Coherence resonance in the system with periodical potential and driven by correlated noises

We study the ratchet model with both thermal and potential fluctuations, discussing analytically the coherence resonance of the particle moving in such a potential field. It is found that the correlation between the thermal and potential fluctuations has significant effect on the coherence of the system, i.e. negative correlation enhances the coherence of the system greatly, and with positive correlation, there appears the phenomenon that the coherence suppression and enhancement occur alternatively as the additive noise becomes larger.