Ratchet Effects

Participating group members: Peter Reimann, Mykhaylo Evstigneev
Main cooperation partners: Chris Van den Broeck, Andreas Engel, Peter Hänggi, Roger Filliger

ratchet Ratchet and pawl: The gas molecules hitting the propeller cause the gear to turn, but which way does it go? If spring and pawl work ``correctly'', the gear can only turn counterclockwise. But when thermal noise causes the spring to release and reengage, the gear tends to turn clockwise because of the asymmetry of the gear teeth. This effect dominates whenever more heat is applied to the spring than to the gas.

We address the question, how the interplay of a nonlinear dynamics and unbiased random fluctuations may generate directed macroscopic transport in spatially periodic structures. This so-called ratchet effect arises, for instance, when the symmetry of a periodic potential is broken (ratchet potential). Besides its theoretical interest as a nonlinear stochastic process far from thermal equilibrium (see figure) this mechanism plays an important role in the context of biological transport (e.g. in motor enzymes, and ion pumps) and nano-technological applications like particle separation and particle pumps (see links to own projects below).

A comprehensive review:

P. Reimann
Brownian Motors: Noisy Transport far from Equilibrium
Phys. Rep. 361, 57 (2002)

Papers covering both theory and experiments:

A. Engel, H. W. Müller, P. Reimann, and A. Jung
Ferrofluids as thermal ratchets
Phys. Rev. Lett 91, 060602 (2003)
This work is summarized in a poster and illustrated by a movie (1.4 MB).

D. van der Meer, P. Reimann, K. van der Weele, and D. Lohse
Spontaneous Ratchet Effect in a Granular Gas
Phys. Rev. Lett. 92, 184301 (2004)
This work is illustrated by a movie (32 MB).

P. Tierno, P. Reimann, T.H. Johansen, and F. Sagues
Giant Transversal Particle Diffusion in a Longitudinal Magnetic Ratchet
Phys. Rev. Lett. 105, 230602 (2010), Physical Review Focus

L. Bogunovic, R. Eichhorn, J. Regtmeier, D. Anselmetti, and P. Reimann
Particle sorting by a structured microfluidic ratchet device with tunable selectivity: theory and experiment
Soft Matter 8, 3900 (2012)

A selection of basic theoretical studies:

R. Bartussek, P. Reimann, and P. Hänggi
Precise Numerics versus Theory for Correlation Ratchets
Phys. Rev. Lett. 76, 1166 (1996)

P. Reimann, R. Bartussek, R. Häussler, and P. Hänggi
Brownian Motors Driven by Temperature Oscillations
Phys. Lett. A 215, 26 (1996)

P. Reimann
Supersymmetric Ratchets
Phys. Rev. Lett. 86, 4992 (2001)

P. Reimann and M. Evstigneev
Pulsating potential ratchet
Europhys. Lett. 78, 50004 (2007)

R. Filliger and P. Reimann
Brownian Gyrator: A Minimal Heat Engine on the Nanoscale
Phys. Rev. Lett. 99, 230602 (2007)

S. von Gehlen, M. Evstigneev, and P. Reimann
Dynamics of a dimer in a symmetric potential: Ratchet effect generated by an internal degree of freedom
Phys. Rev. E 77, 031136 (2008)

S. von Gehlen, M. Evstigneev, and P. Reimann
Ratchet effect of a dimer with broken friction symmetry in a symmetric potential
Phys. Rev. E 79, 031114 (2009)

Theoretical predictions which have later been verified by experimental groups
(see Science 286, 2314 (1999), Science 300, 1235 (2003), and Nature 424, 53 (2003), respectively)

P. Reimann, M. Grifoni, and P. Hänggi
Quantum Ratchets
Phys. Rev. Lett. 79, 10 (1997)

P. Reimann
Current Reversal in a White Noise driven flashing Ratchet
Phys. Rep. 290, 149 (1997)

C. Kettner, P. Reimann, P. Hänggi, and F. Müller
Drift Ratchet
Phys. Rev. E 61, 312 (2000)

Related links:

Our own project on new migration mechanisms in microfluidic systems

Our own project on granular gases

Our own project on noise-induced collective phenomena far from equilibrium

Our own project on decay of complex metastable states

Our own project on open quantum systems

Animated flashing ratchet

Parrondo's games

Molecular motor animation

Last modified on 2012-03-14