Recent measurements for the ionization energies of the Rydberg singlet-P and triplet-P states of helium for principal quantum number $n = 24$ to 100 [1] present a new challenge to high-precision atomic theory. A long-standing obstacle is that the accuracy of variational calculations for two-electron systems rapidly declines with increasing $n$. The problem has now become urgent with the...
Astrophysical radiative transfer models typically assume that atoms and molecules emit and absorb radiation independently. However, recent evidence suggests that cooperative quantum effects—such as superradiance and potentially subradiance—can significantly alter radiative behavior.
Superradiance, a cooperative quantum emission process, has been observed in star-forming regions, where it...
