We review a family of models recently introduced to describe Brownian motors under the influence of Coulomb friction, or more general non-linear friction laws. It is known that, if the heat bath is modeled as the usual Langevin equation (linear viscosity plus white noise), additional non-linear friction forces are not sufficient to break detailed balance, i.e. cannot produce a motor effect. We discuss two possibile mechanisms to elude this problem. A first possibility, exploited in several models inspired to recent experiments, is to replace the heat bath's white noise by a “collisional noise”, that is the effect of random collisions with an external equilibrium gas of particles. A second possibility is enlarging the phase space, e.g. by adding an external potential which couples velocity to position, as in a Klein—Kramers equation. In both cases, non-linear friction becomes sufficient to achieve a non-equilibrium steady state and, in the presence of an even small spatial asymmetry, a motor effect is produced.

Coulomb Friction Driving Brownian Motors / Manacorda, Alessandro; Puglisi, Andrea; Sarracino, Alessandro. - In: COMMUNICATIONS IN THEORETICAL PHYSICS. - ISSN 0253-6102. - STAMPA. - 62:4(2014). [10.1088/0253-6102/62/4/08]

Coulomb Friction Driving Brownian Motors

MANACORDA, ALESSANDRO;PUGLISI, Andrea;SARRACINO, ALESSANDRO
2014

Abstract

We review a family of models recently introduced to describe Brownian motors under the influence of Coulomb friction, or more general non-linear friction laws. It is known that, if the heat bath is modeled as the usual Langevin equation (linear viscosity plus white noise), additional non-linear friction forces are not sufficient to break detailed balance, i.e. cannot produce a motor effect. We discuss two possibile mechanisms to elude this problem. A first possibility, exploited in several models inspired to recent experiments, is to replace the heat bath's white noise by a “collisional noise”, that is the effect of random collisions with an external equilibrium gas of particles. A second possibility is enlarging the phase space, e.g. by adding an external potential which couples velocity to position, as in a Klein—Kramers equation. In both cases, non-linear friction becomes sufficient to achieve a non-equilibrium steady state and, in the presence of an even small spatial asymmetry, a motor effect is produced.
2014
01 Pubblicazione su rivista::01a Articolo in rivista
Coulomb Friction Driving Brownian Motors / Manacorda, Alessandro; Puglisi, Andrea; Sarracino, Alessandro. - In: COMMUNICATIONS IN THEORETICAL PHYSICS. - ISSN 0253-6102. - STAMPA. - 62:4(2014). [10.1088/0253-6102/62/4/08]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/933170
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