  We study the diffusive dynamics of a Brownian particle in proximity of a flat
surface under non-equilibrium conditions, which are created by an anisotropic
thermal environment with different temperatures being active along distinct
spatial directions. By presenting the exact time-dependent solution of the
Fokker-Planck equation for this problem, we demonstrate that the interplay
between anisotropic diffusion and hard-core interaction with the plain wall
rectifies the thermal fluctuations and induces directed particle transport
parallel to the surface, without any deterministic forces being applied in that
direction. Based on current micromanipulation technologies, we suggest a
concrete experimental set-up to observe this novel noise-induced transport
mechanism. We furthermore show that it is sensitive to particle
characteristics, such that this set-up can be used for sorting particles of
different size.
