title: Flux reversal in a two-state symmetric optical thermal ratchet.
abstract: A Brownian particle's random motions can be rectified by a periodic potential-energy landscape that alternates between two states, even if both states are spatially symmetric. If the two states differ only by a discrete translation, the direction of the ratchet-driven current can be reversed by changing their relative durations. We experimentally demonstrate flux reversal in a symmetric two-state ratchet by tracking the motions of colloidal spheres moving through large arrays of discrete potential-energy wells created with dynamic holographic optical tweezers. The model's simplicity and high degree of symmetry suggest possible applications in molecular-scale motors.
authors.affiliation: Department of Physics and Center for Soft Matter Research, New York University, New York, New York 10003, USA.
authors.forename: Sang-Hyuk
authors.initials: SH
authors.lastname: Lee
authors.forename: David G
authors.initials: DG
authors.lastname: Grier
mesh_terms: D003198:Computer Simulation; D004058:Diffusion; D004735:Energy Transfer; D006358:Hot Temperature; D008863:Microspheres; D008956:Models, Chemical; D008968:Molecular Conformation; D020409:Molecular Motor Proteins / Q000737:chemistry* / Q000528:radiation effects* / Q000648:ultrastructure; D009038:Motion; D055095:Optics and Photonics; D010316:Particle Size; D044367:Phase Transition; D012822:Silicon Dioxide / Q000737:chemistry / Q000528:radiation effects
chemical_list: D020409:Molecular Motor Proteins; D012822:Silicon Dioxide