Stochastic resonance in a surface dipole

The occurrence of stochastic resonance for overdamped neutral dipoles
confined on a periodic substrate is discussed. The dipole is made up of
two bound equal monomers carrying opposite charges and suspended in a
viscous medium. Elastic dimers of this kind can be used to represent,
for instance, tiny fragments of longer and more complex molecular
chains, as is often the case in DNA electrophoresis, or neutral
molecular segments stretched between two charged synthetic beads. At
variance with the case of a single monomer in a periodic potential, a
directed neutral dipole exhibits stochastic resonance. Namely, the
combination of dipole binding and substrate generates the bistable (or
multistable) effective potential necessary for the manifestation of
stochastic resonance. Such a phenomenon can be interpreted as a
thermally induced resonance, where the amplitude of the forced
oscillations of a directed dipole attains a maximum at an optimal
substrate temperature. Such a manifestation of stochastic resonance
turns out to be extremely sensitive to the mechanical properties of the
dipole, in particular of the dimer binding potential. Whereas the
stochastic resonance mechanism reported is highly selective with respect
to the length and elasticity of the dipole, it can have important
technological applications.