Mobility and stochastic resonance in spatially inhomogeneous systems.

The mobility of an overdamped particle, in a periodic potential tilted by a constant external field and moving in a medium with periodic friction coefficient is examined. When the potential and the friction coefficient have the same periodicity but have a phase difference, the mobility shows many interesting features as a function of the applied force, the temperature, etc. The mobility shows stochastic resonance even for constant applied force, an issue of much recent interest. The mobility also exhibits a resonance-like phenomenon as a function of the field strength and noise induced slowing down of the particle in an appropriate parameter regime.