A Rydberg polaron is an exotic

state of matter In physics, a state of matter is one of the distinct forms in which matter can exist. Four states of matter are observable in everyday life: solid, liquid, gas, and plasma. Many intermediate states are known to exist, such as liquid crystal, ...

, created at low temperatures, in which a very large atom contains other ordinary atoms in the space between the nucleus and the electrons. For the formation of this atom, scientists had to combine two fields of atomic physics:

Bose–Einstein condensate In condensed matter physics, a Bose–Einstein condensate (BEC) is a state of matter that is typically formed when a gas of bosons at very low densities is cooled to temperatures very close to absolute zero (−273.15 °C or −459.6 ...

s and

Rydberg atom A Rydberg atom is an excited atom with one or more electrons that have a very high principal quantum number, ''n''. The higher the value of ''n'', the farther the electron is from the nucleus, on average. Rydberg atoms have a number of peculi ...

s. Rydberg atoms are formed by exciting a single atom into a high-energy state, in which the electron is very far from the nucleus. Bose–Einstein condensates are a state of matter that is produced at temperatures close to absolute zero. Polarons are induced by using a laser to excite Rydberg atoms contained as impurities in a Bose–Einstein condensate. In those Rydberg atoms, the average distance between the electron and its nucleus can be as large as several hundred nanometres, which is more than a thousand times the radius of a hydrogen atom. Under these circumstances, the distance between the nucleus and the electron of the excited Rydberg atoms is higher than the average distance of the atoms of the condensate. As a result, some atoms lie inside the orbit of the Rydberg atom's electron. As the atoms don't have an electric charge, they only produce a minimal force on the electron. However, the electron is slightly scattered at the neutral atoms, without even leaving its orbit, and the weak bond that is generated between the Rydberg atom and the atoms inside of it, tying them together, is known as the Rydberg polaron. The new state of matter was predicted by theorists at Harvard University in 2016 and confirmed in 2018 by

spectroscopy Spectroscopy is the field of study that measures and interprets the electromagnetic spectra that result from the interaction between electromagnetic radiation and matter as a function of the wavelength or frequency of the radiation. Matter ...

in an experiment using a strontium Bose–Einstein condensate. Theoretically, up to 170 ordinary strontium atoms could fit closely inside the new orbital of the Rydberg atom, depending on the radius of the Rydberg atom and the density of the Bose–Einstein condensate. The theoretical work for the experiment was performed by theorists at

Vienna University of Technology TU Wien (TUW; german: Technische Universität Wien; still known in English as the Vienna University of Technology from 1975–2014) is one of the major universities in Vienna, Austria. The university finds high international and domestic recogn ...

and

Harvard University Harvard University is a private Ivy League research university in Cambridge, Massachusetts. Founded in 1636 as Harvard College and named for its first benefactor, the Puritan clergyman John Harvard, it is the oldest institution of highe ...

, while the actual experiment and observation took place at

Rice University William Marsh Rice University (Rice University) is a Private university, private research university in Houston, Houston, Texas. It is on a 300-acre campus near the Houston Museum District and adjacent to the Texas Medical Center. Rice is ranke ...

in Houston, Texas.

References

{{Reflist

External links

Creation of Rydberg Polarons in a Bose Gas
original article at Physical Review Letters. Condensed matter physics Exotic matter Phases of matter

See also

References

External links