Center for Nonlinear Dynamics and Department of Physics, University of Texas at Austin, Austin, TX 78712, USA.
Science. 2010 Jun 25;328(5986):1673-5. doi: 10.1126/science.1189403. Epub 2010 May 20.
Brownian motion of particles affects many branches of science. We report on the Brownian motion of micrometer-sized beads of glass held in air by an optical tweezer, over a wide range of pressures, and we measured the instantaneous velocity of a Brownian particle. Our results provide direct verification of the energy equipartition theorem for a Brownian particle. For short times, the ballistic regime of Brownian motion was observed, in contrast to the usual diffusive regime. We discuss the applications of these methods toward cooling the center-of-mass motion of a bead in vacuum to the quantum ground motional state.
粒子的布朗运动影响着许多科学分支。我们报告了在广泛的压力范围内，通过光学镊子悬浮在空气中的玻璃微球的布朗运动，并测量了布朗粒子的瞬时速度。我们的结果直接验证了布朗粒子的能量均分定理。在短时间内，观察到了布朗运动的弹道阶段，而不是通常的扩散阶段。我们讨论了这些方法在将真空中的珠子的质心运动冷却到量子基态运动的应用。
