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Physics World

Positronium gas is laser-cooled to one degree above absolute zero

Isabelle Dumé

Published Nov 1, 2024• 0 citations
Publisher

Abstract

Researchers at the University of Tokyo have used a new laser technique to cool a gas of positronium atoms to temperatures as low as 1 K.
DOI
10.1088/2058-7058/37/11/05

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INTRODUCTION A variety of techniques have been developed over the past two decades for influencing the motion of atomic gases using laser light. These techniques, termed collectively 'laser cooling,' produce samples of atoms with temperatures one millionth of a degree above absolute zero, ushering in a new era of atomic physics. The exquisite control offered by these techniques has made possible measurements of fundamental constants, atomic clocks used in the realization of the SI unit of time, new atom-wave interferometers, and the realization of Bose-Einstein condensation. To understand the impact of gravity on such cold atoms, consider that if the atmosphere were an ideal gas cooled to one micro-Kelvin, it would only extend just 5 microns above the Earth's surface.