Helium tune-out wavelength: Gauge invariance and retardation corrections

@article{Drake2019HeliumTW,
  title={Helium tune-out wavelength: Gauge invariance and retardation corrections},
  author={Gordon William Frederic Drake and Jerome G. Manalo and P.-P. Zhang and Kenneth G. H. Baldwin},
  journal={Hyperfine Interactions},
  year={2019},
  volume={240},
  pages={1-9}
}
The problem of calculating the tune-out wavelength for an atom interacting with a plane electromagnetic wave is formulated as a zero in the Rayleigh scattering cross section, rather than a zero in the dynamic polarizability. Retardation (finite wavelength) corrections are discussed in the velocity gauge, and possible gauge transformations to a length form are investigated. For the special case of S-states, it is shown that a pure length form exists for the leading pxz retardation correction… CONTINUE READING