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Volume 592 Issue 7852, 1 April 2021

Laser-cooled antimatter

Laser cooling — the use of photons to slow the movement of atoms — changed the face of atomic physics when it was first demonstrated 40 years ago. In this week’s issue, the ALPHA collaboration takes this technique into fresh territory by successfully applying it to antimatter. Working at CERN’s Antiproton Decelerator facility, the researchers trapped atoms of antihydrogen using magnetic fields and then irradiated them with carefully tuned pulses of a purpose-built, ultraviolet laser. This slowed some of the atoms down, thereby cooling them and reducing the width of a measured atomic transition in the anti-atoms. The researchers believe the technique should make it easier to investigate the fundamental properties of antimatter — including its gravitational behaviour. The cover shows a close-up of the end electrode of the gold-plated Penning trap that is used to capture and manipulate antiprotons and positrons to form the antihydrogen atoms.

Cover image: Niels Madsen/ALPHA/Swansea Univ.

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