Thursday, March 15, 2012

1203.2751 (David Speer et al.)

Anisotropic diffusion in square lattice potentials: giant enhancement
and control
   [PDF]

David Speer, Ralf Eichhorn, Peter Reimann
The unbiased thermal diffusion of an overdamped Brownian particle in a square lattice potential is considered in the presence of an externally applied ac driving. The resulting diffusion matrix exhibits two orthogonal eigenvectors with eigenvalues $D_1>D_2>0$, indicating anisotropic diffusion along a "fast" and a "slow principal axis". For sufficiently small temperatures, $D_1$ may become arbitrarily large and at the same time $D_2$ arbitrarily small. The principal diffusion axis can be made to point into (almost) any direction by varying either the driving amplitude or the coupling of the particle to the potential, without changing any other property of the system or the driving.
View original: http://arxiv.org/abs/1203.2751

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