Invisible helium atoms provide exquisitely sensitive test of fundamental theory

The most sensitive method for measuring the potential energy of an atom has been developed by physicists at the Australian National University.

The research, published this week in Science, is an independent corroboration of previous methods used to test QED, which have involved measuring transitions from one atomic energy state.

The invisibility is only for a specific atom and a specific colour of light, so it couldn't be used to make an invisibility cloak that Harry Potter would use to investigate dark corners at Hogwarts.

We were able to investigate some dark corners of QED theory.

We were hoping to catch QED out, because there have been some previous discrepancies between theory and experiments, but it passed with a pretty good mark.

In the late 1940s, QED was developed and describes how light and matter interact, incorporating both quantum mechanics and Einstein's special theory of relativity in a way that has remained successful for nearly eighty years.

There werediscrepancies in the size of the protons which were mostly resolved in 2019.

There was a Bose-Einstein condensate and a very sensitive experiment being conducted by a ANU Scholar.

He measured the frequencies with record precision, and found that the atoms and the laser light had an effect on the frequencies.

The effect could be used to determine the exact colour of the atoms that did not interact with the laser, and the oscillation remained the same.

The team achieved a sensitivity in their energy measurement that was 5 orders of magnitude less than the energy of the atoms, with the combination of an extremely high-resolution laser and atoms cooled to 80 billionths of a degree above absolute zero.

It is so far off the end of the scale that I cannot think of any phenomenon to compare it to.

The team was able to deduce very precise values for the invisibility colour of helium. To compare their results with theoretical prediction for QED, they turned to Professor Li-Yan Tang from the Chinese Academy of the Sciences in Wuhan and Professor Gordon Drake from the University of Windsor in Canada.

The theoreticians had to rise to the challenge and improve their calculations because previous calculations using QED had less uncertainty than the experiments.

They were able to improve their uncertainty to a mere 40th of the latest experimental uncertainty, and singling out the QED contribution to the atom's invisibility frequencies which was 30 times larger than the experiment's uncertainty.

The leader of the international collaboration, Professor Ken Baldwin from the ANU Research School of Physics, said that improvements to the experiment might help resolve the discrepancy, but would also hone an extraordinary tool that could illuminate QED and other theories.

Big changes in theoretical understanding can be driven by new tools for precision measurement.

More information: B. M. Henson et al, Measurement of a helium tune-out frequency: an independent test of quantum electrodynamics, Science (2022). DOI: 10.1126/science.abk2502 Journal information: Science Citation: Invisible helium atoms provide exquisitely sensitive test of fundamental theory (2022, April 8) retrieved 8 April 2022 from https://phys.org/news/2022-04-invisible-helium-atoms-exquisitely-sensitive.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.