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Optical trapping and cooling of glass microspheresFormat | Member Price | Non-Member Price |
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Paper Abstract
We report on experiments studying the Brownian motion of an optically trapped bead in air, and observe for the first
time the short-time regime of ballistic motion. Einstein predicted this effect in 1907, but said the experiment would be
impossible in practice. Our measurements were enabled by our development of a new detection system that is capable of
real-time tracking of the motion of a trapped bead on unprecedented short time scales and correspondingly small length
scales. We used the data to measure the average kinetic energy of a Brownian particle, and find good agreement with
the energy equipartition theorem of statistical mechanics. Measurement of the instantaneous velocity also allows us to
stably trap beads in vacuum, using active feedback to control and cool the center of mass motion to mK temperatures in
three dimensions. The system of an optically trapped bead in vacuum can serve as a testing ground for macroscopic
quantum superpositions and the role of decoherence. In the opposite extreme, a trapped bead in a fluid can be used to test
basic questions in statistical mechanics, and fluid dynamics on the smallest scales.
Paper Details
Date Published: 10 October 2012
PDF: 7 pages
Proc. SPIE 8458, Optical Trapping and Optical Micromanipulation IX, 84580B (10 October 2012); doi: 10.1117/12.928885
Published in SPIE Proceedings Vol. 8458:
Optical Trapping and Optical Micromanipulation IX
Kishan Dholakia; Gabriel C. Spalding, Editor(s)
PDF: 7 pages
Proc. SPIE 8458, Optical Trapping and Optical Micromanipulation IX, 84580B (10 October 2012); doi: 10.1117/12.928885
Show Author Affiliations
Mark G. Raizen, The Univ. of Texas at Austin (United States)
Simon Kheifets, The Univ. of Texas at Austin (United States)
Simon Kheifets, The Univ. of Texas at Austin (United States)
Tongcang Li, The Univ. of Texas at Austin (United States)
Published in SPIE Proceedings Vol. 8458:
Optical Trapping and Optical Micromanipulation IX
Kishan Dholakia; Gabriel C. Spalding, Editor(s)
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