Abstract:
Molecular motors are nanodevices, either man-made or occurring inside living cells, which convert heat into ordered motion, at the expense of external reservoirs, which keep the system far from equilibrium. The now-classic example is the Smoluchowski-Feynman ratchet. In our talk we present our recent contributions to the long-standing problem of the enormous efficiency of the biological motors, which contrasts with the efficiency of a few percent found in artificial systems.
We investigate the model of ``reversible ratchet'' with interacting particles. We calculate their energetic efficiency, when acting as molecular motors carrying a load against external force. It is shown that interaction between particles enhances the efficiency in wide range of parameters. We show that the effect has energetic, rather than entropic, origin. We also show complicated structures emerging in the interaction and density dependence of the current and response function. The fluctuation properties of the work and input energy indicate in detail the far-from-equilibrium nature of the dynamics. Besides the simulation results we show that a rather sophisticated mean-field-like approximation grasps well the phenomenon of the efficiency increase and yields further quantities, especially the non-Gaussian large-deviation function for work fluctuations. Possible consequences for artificial molecular motors are discussed.
References:
[1] F. Slanina, EPL 84 (2008) 50009