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Updated: Jan 20, 2026

Cooling an Optically Trapped Ultracold Fermi Gas by Periodical Driving
Published on: March 30, 2017
Measurement of the variation of electron-to-proton mass ratio using ultracold molecules produced from laser-cooled
J Kobayashi1,2, A Ogino3, S Inouye4,5
1Department of Physics, Graduate School of Science, Kyoto University, Kyoto, 606-8502, Japan. j-kobayashi@scphys.kyoto-u.ac.jp.
Abstract:
Experimental techniques to manipulate cold molecules have seen great development in recent years. The precision measurements of cold molecules are expected to give insights into fundamental physics. Here we use a rovibrationally pure sample of ultracold KRb molecules to improve the measurement on the stability of electron-to-proton mass ratio [Formula: see text]. The measurement is based upon a large sensitivity coefficient of the molecular spectroscopy, which utilizes a transition between a nearly degenerate pair of vibrational levels each associated with a different electronic potential. Observed limit on temporal variation of μ is [Formula: see text], which is better by a factor of five compared with the most stringent laboratory molecular limits to date. Further improvements should be straightforward, because our measurement was only limited by statistical errors.
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