Brownian vortex induced by optical tweezers

Bo Sun, Alexander Y. Grosberg, David G. Grier

    Research output: Chapter in Book/Report/Conference proceedingConference contribution


    A particle diffusing around a point of stable mechanical equilibrium in a static but non-conservative force field enters into a steady state characterized by circulation in the probability flux. Circulation in such a Brownian vortex is not simply a deterministic response to the solenoidal component of the force, but rather reflects an interplay between force-driven probability currents and diffusion. As an example of this previously unrecognized class of stochastic heat engines, we consider a colloidal sphere stably trapped in a conventional optical tweezer. Rather than coming into thermodynamic equilibrium with the surrounding heat bath, the particle's Brownian fluctuations are biased into a toroidal roll. We demonstrate both theoretically and experimentally that the circulation in this practical realization of the Brownian vortex can undergo flux reversal.

    Original languageEnglish (US)
    Title of host publicationFrontiers in Optics, FiO 2009
    PublisherOptical Society of America
    ISBN (Print)9781557528780
    StatePublished - Jan 1 2009
    EventFrontiers in Optics, FiO 2009 - San Jose, CA, United States
    Duration: Oct 11 2009Oct 15 2009

    Publication series

    NameOptics InfoBase Conference Papers
    ISSN (Electronic)2162-2701


    OtherFrontiers in Optics, FiO 2009
    Country/TerritoryUnited States
    CitySan Jose, CA

    ASJC Scopus subject areas

    • Instrumentation
    • Atomic and Molecular Physics, and Optics


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