Precision spectroscopy of helium in a magic wavelength optical dipole trap

TL;DR

This paper reports the most precise measurement of a helium optical transition using a Bose-Einstein condensate in a magic wavelength trap, providing stringent tests of QED, atomic polarizability, and nuclear size.

Contribution

It combines Bose-Einstein condensation with magic wavelength trapping to achieve unprecedented precision in helium spectroscopy, testing fundamental physics theories.

Findings

High-precision helium transition measurement achieved

Validation of polarizability calculations and scattering properties

Probing nuclear size with unprecedented accuracy

Abstract

Improvements in both theory and frequency metrology of few-electron systems such as hydrogen and helium have enabled increasingly sensitive tests of quantum electrodynamics (QED), as well as ever more accurate determinations of fundamental constants and the size of the nucleus. At the same time advances in cooling and trapping of neutral atoms have revolutionized the development of increasingly accurate atomic clocks. Here, we combine these fields to reach the highest precision on an optical tranistion in the helium atom to date by employing a Bose-Einstein condensate confined in a magic wavelength optical dipole trap. The measured transition accurately connects the ortho- and parastates of helium and constitutes a stringent test of QED theory. In addition we test polarizability calculations and ultracold scattering properties of the helium atom. Finally, our measurement probes the size of the nucleus at a level exceeding the projected accuracy of muonic helium measurements currently being performed in the context of the proton radius puzzle.