What are the properties and characteristics of a Rydberg state in atomic physics?

A Rydberg state in atomic physics is a high-energy state where an electron is located far from the nucleus. This results in a large atomic radius and a long lifetime for the electron. Rydberg states have unique properties such as high principal quantum numbers, low ionization energies, and strong interactions with external fields. These states are important for studying atomic and molecular physics, as well as for applications in quantum technology.