Zenith Grant Awardee

Dr. Dmitry Budker

University of California at Berkeley

Co-Investigators

Alain Lapierre, <i>University of California at Berkeley</i><br>Arman Cingoz, <i>University of California at Berkeley</i><br>Nathan Leefer, <i>University of California at Berkeley </i>

Project Title

Search for a Possible Time Variation of the Fine-Structure Constant alpha by Radio-Frequency Spectroscopy of Atomic Dysprosium

Project Summary

The development of physical theories has relied on the constancy of various fundamental quantities. Detecting or constraining possible spatial or temporal variations of fundamental physical constants is essential for a complete understanding of the Universe and the development of an ultimate theory of matter, space, and time, unifying the force of gravity with electromagnetism and the strong and weak nuclear forces.

The fine-structure constant, alpha, is a "constant" that depends on the electron charge and the speed of light. It dictates the strength of the interaction between light and matter and critically determines the wavelength of the light emitted or absorbed by atoms. Recent astrophysical observations indicate an alpha variation. We propose a search for a change of alpha of a few parts in one billion billion per year by investigating small time variations of the energy of radio-waves absorbed by atoms of dysprosium exceptionally sensitive to alpha variation.

Discovery of alpha variation would have a significant impact on our fundamental views on Nature. This would contradict Einstein's theory of relativity and indicate new physics beyond current models. It would support the existence of extra space-time dimensions or could be the signature of additional fundamental forces.

Technical Abstract

In Einstein's general theory of relativity space-time variations of fundamental constants are forbidden since they violate Einstein's equivalence principle. However, they are allowed and/or needed in modern theories aiming at unifying gravitation with quantum mechanics, such as String theories including extra space-time dimensions. Searches for such variations test and investigate the possibility of new physics beyond general relativity and the Standard Model.

We propose a laboratory search for temporal variation of the coupling constant between light and matter, alpha (fine-structure constant), exceeding the sensitivity level of the best atomic-clock laboratory and quasar-absorption searches by three and two orders of magnitude, respectively. Our experimental technique uses radio-frequency spectroscopy of electric-dipole transitions between nearly degenerate opposite-parity energy levels in atomic dysprosium and has been designed to address the question of the constancy of alpha. The energies of these transitions are highly sensitive to alpha variation. Such transitions will enable us to reach an unprecedented sensitivity of 10^(-18)/year to its temporal fractional variation. If the controversial astrophysical results indicating an alpha variation are confirmed, this sensitivity will uniquely allow for observation of changes in alpha in real time and might reveal short-time fluctuations in the variation, opening a new era in physics.