circular state

English

Etymology

Named after the torus-like shape of the valence electron orbital in these states, which resembles a classical circular orbit.

Noun

circular state (plural circular states)

1. (physics) Any of those quantum states of an atom, which has a high principal quantum number $n$, and a magnetic quantum number $m_{l}$ with the maximum possible magnitude, $|m_{l}|=n-1$.
   • 1962 December, J.R. Rook, “The decay of K⁻ mesic atoms”, in Nuclear Physics, volume 39, →DOI, page 479:

     It has been shown ^3,4) that the selection rules on the Auger and X-ray transition probabilities tend to populate preferentially the circular states, that is those for which the orbital angular momentum $l$ is given by $l=n-1$.

   • 1983 October 17, Randall G. Hulet and Daniel Kleppner, “Rydberg Atoms in "Circular" States”, in Physical Review Letters, volume 51, →DOI, page 1430:

     We report the production of a population of atoms in a Rydberg state with $|m|=n-1$, where $m$ and $n$ are the magnetic and principal quantum numbers, respectively. We designate these states as "circular" because in the classical limit they describe an electron in a circular orbit. Among all the states with a given principal quantum number, the circular states have the largest magnetic moment, smallest Stark effect, and longest radiative lifetime.

   • 2021 August 6, Sam R. Cohen and Jeff D. Thompson, “Quantum Computing with Circular Rydberg Atoms”, in PRX Quantum, volume 2, →DOI, page 030322:

     So-called circular states with the maximal angular momentum $L=n-1$ can have lifetimes exceeding 100 s, $10^{6}$ times longer than those of low-$L$ states, in appropriately engineered environments.