Author ORCID Identifier
tune-out wavelength, gauge transformation, retardation, helium
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, even though one does not exist in general. The results of high-precision calculations in Hylleraas coordinates are presented for the tune-out wavelength of helium near the 2 3S - 3 3P transition at 413 nm.
Funding Reference Number
Drake, Gordon W. F.; Manalo, Jacob Gabriel; Zhang, Pei-Pei; and Baldwin, Kenneth George Herbert. (2019). Helium tune-out wavelength: Gauge invariance and retardation corrections. Hyperfine Interactions.