Monday, February 7, 2011

talk by Mark Raizen

Mark is discussing how the Brownian motion of macroscopic objects can be controlled. Fabricated microsphere (~ 1 micron diameter) are launched in high voltage and shaken off in air. The largest force turns out to be van der Waals force. The beads scatter photons in the focus of the laser beam. The power spectra of a 3.01 micron bead were shown. The time scale for a 3 micron silica instantaneous motion (velocity) is about 1.2 micro-sec for water and 56 micro-sec for air, giving a resolution restriction of about 100 nano-sec and 4 pico-meter for H_2O and more forgiving for air. The test of equipartition theorem is confirmed.

Now the challenge is to confirm the Brownian motion is water. Preliminary results appear to show ballistic motion- possible breakdown of the equipartition theorem? It shall be seen.

Moving toward the quantum limit; mK cooling of microbeads has been achieved. In arXiv, accepted for publication. Applications: spraying charges and using as thermometer, or for sympathetic cooling of antihydrogen.

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