Prof. Aharon Kapitulnik, Stanford University

Date: Mar. 18, 2007

Title: Search for Gravity-like Forces at sub-mm distance

Abstract:

Recent theories of physics beyond the standard model have predicted
deviations from Newtonian gravity at short distances. In order to test
these theories, we have a built an apparatus that can measure
attonewton-scale forces between small masses separated by distances on
the order of 25 microns. A micromachined silicon cantilever was used
as the force sensor, and its displacement was measured with a fiber
interferometer. We have used our measurements to set bounds on the
magnitude alpha and length scale lambda of Yukawa-type deviations from
Newtonian gravity; our results presented here yield the best
experimental limit in the range of lambda between 5 and 50 microns.
We also discuss initial results from new experiments in which
substantial improvements are expected.