Phys. Rev. Lett. 104, 248001 (2010) [4 pages]Experimental Realization of a Rotational Ratchet in a Granular GasReceived 10 March 2009; revised 29 October 2009; published 16 June 2010 We construct a ratchet of the Smoluchowski-Feynman type, consisting of four vanes that are allowed to rotate freely in a vibrofluidized granular gas. The necessary out-of-equilibrium environment is provided by the inelastically colliding grains, and the equally crucial symmetry breaking by applying a soft coating to one side of each vane. The onset of the ratchet effect occurs at a critical shaking strength via a smooth, continuous phase transition. For very strong shaking the vanes interact actively with the gas and a convection roll develops, sustaining the rotation of the vanes. © 2010 The American Physical Society URL:
http://link.aps.org/doi/10.1103/PhysRevLett.104.248001
DOI:
10.1103/PhysRevLett.104.248001
PACS:
45.70.-n, 05.40.-a, 83.10.Mj
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