Close

Search

Search Menu
Photonics Media Photonics Buyers' Guide Photonics EDU Photonics Spectra BioPhotonics EuroPhotonics Industrial Photonics Photonics Showcase Photonics ProdSpec Photonics Handbook
More News
SPECIAL ANNOUNCEMENT
2016 Photonics Buyers' Guide Clearance! – Use Coupon Code FC16 to save 60%!
share
Email Facebook Twitter Google+ LinkedIn Comments

Laser-Cooling Measures Quantum-Mechanical

Photonics Spectra
Nov 1999
A team of researchers at Stanford University in California have confirmed that the value of g, acceleration caused by gravity, is constant with respect to mass and size. The physicists employed laser cooling to construct an atom interferometer that measured the rate of fall of cesium atoms. They found that the atoms experienced an acceleration that agreed with the g on macroscopic objects to within seven parts in a billion.

The team cooled about 5 x 108 atoms to 1.5 µK, launched them with a series of microwave pulses and measured their rate of descent by observing Raman scattering effects on the initial, superposition state of the super-cooled cesium. The researchers used a Michelson interferometer gravimeter to compare the results against the g of a falling prism, which is governed by classical mechanics.

Steven Chu, the 1997 Nobel laureate who developed the laser-cooled, atomic fountain technique and was a member of the team, said the result challenges the speculation that space-time fluctuations affect gravity at the quantum-mechanical level, a suggestion that followed recent experiments that used a neutron interferometer to measure.


Comments
Terms & Conditions Privacy Policy About Us Contact Us
back to top

Facebook Twitter Instagram LinkedIn YouTube RSS
©2016 Photonics Media
x Subscribe to Photonics Spectra magazine - FREE!