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Hybrid matter-antimatter atoms?

Do so-called antimatter particles play by the same rules as normal matter? Having an opposite charge from the electron, for example, does the positron obey the same laws of physics? Yes, essentially. (Baryon asymmetry is an ongoing topic of research as to any tiny effective difference.)

But what happens to atomic dynamics when an electron in a helium atom is replaced with an antiproton?

Laser beams are at play once again, pushing an electron to a higher atomic energy level.

The article (below) kicks off this new post for research on antimatter. Spectroscopy of a superfluid tells a novel tale.

Mash-ups of atomic clouds vary with atomic density in gas, liquid, and superfluid states of helium. Interacting, jostling, overlapping. With different spectral line broadening.

In a normal atom, a tiny electron can venture far from its host atom, especially when excited by a laser. On such a loose leash, the electron can easily bump into other atoms, disturbing its atom’s intrinsic energy levels (and leading to spectral broadening).

Superfluidity takes the edge off atomic collisions in general, …

Why study hybrid atoms? (It’s really pricey!)

Such experiments may allow the physicists to measure certain fundamental constants with unprecedented precision.

• Wired > “An Antimatter Experiment Shows Surprises Near Absolute Zero” by Charlie Wood (May 1, 2022) – Spectral broadening reversed in superfluid hybrid (matter-antimatter) helium.

In 2013, Sótér [professor, Swiss Federal Institute of Technology Zurich] was working at the CERN laboratory on an antimatter experiment. The group would assemble hybrid matter-antimatter atoms by firing antiprotons into liquid helium. Antiprotons are the negatively charged twins of protons, so an antiproton could occasionally take an electron’s place orbiting a helium nucleus. The result was a small cohort of “antiprotonic helium” atoms.

The project was designed to see if spectroscopy in a helium bath was possible at all – a proof of concept for future experiments that would use even more exotic hybrid atoms.