The unidentified helium atoms provide the basic idea test

The unidentified helium atoms provide the basic idea test

A metatable helium Bose-Einstein condensate machine. Available: Tracey Nearmy, Australian National University

Physicists at the Australian National University have developed a very sophisticated method for measuring the energy of an atom (in a percentage of a decillionth of a joule – or 10-35 joules), and used it to confirm any of the ideas tested. .i ka physics – quantum electrodynamics (QED).

The study, published this week by Science relies on detecting the color of a laser light where no helium atom is detected, and is an independent corroboration of the previous methods used to test QED, which involves measuring QED. transitions from one atomic state to another.

“This lack of knowledge is about a specific atom and a specific color of light – so it can’t be used to create the invisible costume that Harry Potter uses to investigate dark corners at Hogwarts,” he said. lead author, Bryce Henson, a Ph..D. student at ANU Research School of Physics.

“But we were able to use the research to explore some of the darker corners of the QED concept.”

“We’re hoping to catch QED, because there were some differences in the past between the concept and the experiments, but it’s gone with a very good signal.”

Quantum Electrodynamics, or QED, was developed in the late 1940s and explained how light and matter interact, combining quantum mechanics with the special concept of electricity. Einstein for relativity as a method that has been practiced for eighty years.

However, QED expects improvements from differences in proton size measurements, which are largely decided in 2019.

Around this time ANU Ph.D. Scholar Bryce Henson observed small oscillations in a very important experiment he was doing on the ultracold world of atoms known as Bose-Einstein condensate.

He measured the frequency of the oscillations with the accuracy of the story, it was found that the relationship between the atoms and the laser light changed in frequency, because the laser color was different.

He found that this effect could be used to accurately determine the exact color so that the atoms were not in contact with the laser and the oscillation did not change – that is, it became invisible.

With the combination of a high -resolution laser and atoms rested at 80 billionths of a degree above zero (80 nanokelvins) the team has achieved a sensitivity to their 5 energy measurements. orders of magnitude below the energy of the atoms, about 10. – 35 joules, or the temperature difference about 10-13 degrees kelvin.

“It’s so small I can’t think of any kind of thing to compare it to – it’s so far from the end of the pound,” Mr Henson said.

With these measurements the team was able to extract the most suitable properties for the invisibility color of helium. To compare their results with the theoretical prediction for QED, they turned to Professor Li-Yan Tang from the Chinese Academy of Science in Wuhan and Professor Gordon Drake from the University of Windsor in Canada.

The initial numbers using QED were not as clear as before the experiments, but with new experimental technology improving accuracy by a score of 20, theoreticians need to wake up to the challenge and improve. in their number.

In this quest, they were more successful than successful – improving their skepticism to only 1 / 40th of the most recent experimental skepticism, and singing the QED’s invisibility frequency. the atom is 30 times larger than the unexplained in the experiment. The value was slightly lower than the experimental value at 1.7 times the ambiguity of the experiment.

The leader of the global group, Professor Ken Baldwin from the ANU Research School of Physics, said that improving the experiment could help correct the inequality, but it would also create an amazing tool that could illuminating QED and other concepts.

“New tools for accurate measurements often bring significant changes to theoretical knowledge down the road,” says Professor Baldwin.


JILA atomic clocks measure Einstein’s standard deviation on the millimeter scale


More information:
BM Henson et al, Measurement of helium tune-out frequency: an independent experiment of quantum electrodynamics, Science (2022). DOI: 10.1126 / science.abk2502

Presented by Australian National University

Directions: Invisible helium atoms provide a simple test of the basic theory (2022, April 8) retrieved April 8, 2022 from https://phys.org/news/2022-04-invisible-helium- atoms-exquisitely-sensitive.html

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