ИСТИНА

Being motivated by recent advances in our understanding protein motors and nanoscale machinery design, we propose a model of energy conversion on the nanoscale, based on the concept of reciprocating motion. The model consists of two coupled Brownian particles fluctuating between two states. The fluctuations are produced by both equilibrium thermal and external nonthermal noise, the transition rates depending on the interparticle distance. An external modulation acts only on the internal degree of freedom (the interparticle distance) and induces reciprocating motion along this coordinate. The system moves unidirectionally due to rectification of the internal movement by asymmetric friction fluctuations and thus operates as a two-headed Brownian motor driven by the free energy input from a nonequilibrium source. The properties of the motor are completely determined by the properties of the reciprocating nanoengine, represented by the interparticle distance dynamics, and a rectifying mechanism. Focusing on the reciprocating engine, we study two basic mechanisms (energetic and informational) underlying noise-induced motion on the nanoscale. For the parabolic potential, we present a few exactly solvable illustrative examples exhibiting a rich behavior of the reciprocating velocity as a function of the model parameters. The design of a symmetry-breaking mechanism to rectify the reciprocating motion is also discussed.