5 research outputs found
Deterministic inhomogeneous inertia ratchets
We study the deterministic dynamics of a periodically driven particle in the
underdamped case in a spatially symmetric periodic potential. The system is
subjected to a space-dependent friction coefficient, which is similarly
periodic as the potential but with a phase difference. We observe that
frictional inhomogeneity in a symmetric periodic potential mimics most of the
qualitative features of deterministic dynamics in a homogeneous system with an
asymmetric periodic potential. We point out the need of averaging over the
initial phase of the external drive at small frictional inhomogeneity parameter
values or analogously low potential asymmetry regimes in obtaining ratchet
current. We also show that at low amplitudes of the drive, where ratchet
current is not possible in the deterministic case, noise plays a significant
role in realizing ratchet current.Comment: 15 pages, 15 figure
Work Fluctuations and Stochastic Resonance
We study Brownian particle motion in a double-well potential driven by an ac
force. This system exhibits the phenomenon of stochastic resonance.
Distribution of work done on the system over a drive period in the time
asymptotic regime have been calculated. We show that fluctuations in the input
energy or work done dominate the mean value. The mean value of work done over a
period as a function of noise strength can also be used to characterise
stochastic resonance in the system. We also discuss the validity of steady
state fluctuation theorems in this particular system.Comment: 5 page
Stochastic resonance and heat fluctuations in a driven double-well system
We study a periodically driven (symmetric as well as asymmetric)double-well
potential system at finite temperature. We show that mean heat loss by the
system to the environment(bath) per period of the applied field is a good
quantifier of stochastic resonance. It is found that the heat fluctuations over
a single period are always larger than the work fluctuations. The observed
distributions of work and heat exhibit pronounced asymmetry near resonance. The
heat losses over a large number of periods satisfies the conventional
steady-state fluctuation theorem, though different relation exists for this
quantity.Comment: modified version, 10 figure