Brownian vortexes

Bo Sun, Jiayi Lin, Ellis Darby, Alexander Y. Grosberg, David G. Grier

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Mechanical equilibrium at zero temperature does not necessarily imply thermodynamic equilibrium at finite temperature for a particle confined by a static but nonconservative force field. Instead, the diffusing particle can enter into a steady state characterized by toroidal circulation in the probability flux, which we call a Brownian vortex. The circulatory bias in the particle's thermally driven trajectory is not simply a deterministic response to the solenoidal component of the force but rather reflects interplay between advection and diffusion in which thermal fluctuations extract work from the nonconservative force field. As an example of this previously unrecognized class of stochastic heat engines, we consider a colloidal sphere diffusing in a conventional optical tweezer. We demonstrate both theoretically and experimentally that nonconservative optical forces bias the particle's fluctuations into toroidal vortexes whose circulation can reverse direction with temperature or laser power.

    Original languageEnglish (US)
    Article number010401
    JournalPhysical Review E - Statistical, Nonlinear, and Soft Matter Physics
    Volume80
    Issue number1
    DOIs
    StatePublished - Aug 6 2009

    ASJC Scopus subject areas

    • Statistical and Nonlinear Physics
    • Statistics and Probability
    • Condensed Matter Physics

    Fingerprint Dive into the research topics of 'Brownian vortexes'. Together they form a unique fingerprint.

    Cite this