What are Rydberg polarons

What is Rydberg Physics?

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Atoms are tiny. Tens of thousands of them could be strung together along one bacterium. But an atom can be "expanded" to almost the size of a microorganism.

How it works?

Roughly speaking, an atom is made up of electrons orbiting around an atomic nucleus. With laser light of precisely measured energy, an electron can be heaved onto a path with a comparatively gigantic diameter. It then circles the core at a distance of a few micrometers. Such colossi of atomic physics are called “Rydberg atoms”, named after the Swedish physicist Johannes Rydberg.

It is not only the size that distinguishes Rydberg atoms from other atoms. The distant atomic nucleus holds the electron only weakly. It is therefore extremely sensitive to external stimuli such as electrical or magnetic fields. Nevertheless, Rydberg atoms are stable for a relatively long time. With its electrical charge, the outermost electron of a Rydberg atom also affects its environment. So it grabs a second atom and catches it. This creates a “Rydberg molecule” that is held together by a completely different type of interaction than a conventional molecule. Rydberg physics knows many other exotic states of matter, such as the so-called Rydberg polaron, in which around a hundred atoms are like a cage in a Rydberg atom.

All of this makes Rydberg atoms extremely interesting research objects for physicists. But groundbreaking applications are also on the horizon.

Text: Christian Meier