Virtual potentials for feedback traps

Yonggun Jun, John Bechhoefer

研究成果: 雜誌貢獻期刊論文同行評審

43 引文 斯高帕斯(Scopus)

摘要

The recently developed feedback trap can be used to create arbitrary virtual potentials, to explore the dynamics of small particles or large molecules in complex situations. Experimentally, feedback traps introduce several finite time scales: There is a delay between the measurement of a particle's position and the feedback response, the feedback response is applied for a finite update time, and a finite camera exposure integrates motion. We show how to incorporate such timing effects into the description of particle motion. For the test case of a virtual quadratic potential, we give the first accurate description of particle dynamics, calculating the power spectrum and variance of fluctuations as a function of feedback gain, testing against simulations. We show that for small feedback gains, the motion approximates that of a particle in an ordinary harmonic potential. Moreover, if the potential is varied in time, for example by varying its stiffness, the work that is calculated approximates that done in an ordinary changing potential. The quality of the approximation is set by the ratio of the update time of the feedback loop to the relaxation time of motion in the virtual potential.

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文章編號061106
期刊Physical Review E - Statistical, Nonlinear, and Soft Matter Physics
86
發行號6
DOIs
出版狀態已出版 - 5 12月 2012

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