Dynamic dipole polarizabilities for the low-lying triplet states of helium

TL;DR

This paper calculates the dynamic dipole polarizabilities, tune-out, and magic wavelengths for helium's low-lying triplet states using a B-spline configuration interaction method, providing results consistent with previous high-precision data.

Contribution

The study introduces accurate calculations of polarizabilities and wavelengths for helium triplet states using the B-spline CI method, including new tune-out and magic wavelength data.

Findings

Static dipole polarizabilities agree with Hylleraas results.

Tune-out wavelength for 2^3S state is 413.038 nm.

Magic wavelength around 1066 nm for specific transitions.

Abstract

The dynamic dipole polarizabilities for the four lowest triplet states ($2\,^3S$, $3\,^3S$, $2\,^3P$ and $3\,^3P$) of helium are calculated using the B-spline configuration interaction method. Present values of the static dipole polarizabilities in the length, velocity and acceleration gauges are in good agreement with the best Hylleraas results. Also the tune-out wavelengths in the range from 400 nm to 4.2~$\mu$m for the four lowest triplet states are identified, and the magic wavelengths in the range from 460~nm to 3.5~$\mu$m for the $2\,^3S \to 3\,^3S$, $2\,^3S \to 2\,^3P$, and $2\,^3S \to 3\,^3P$ transitions are determined. We show that the tune-out wavelength of $2\,^3S$ state is 413.038 28(3) nm, which corroborates the value of Mitroy and Tang (Phys. Rev. A 88, 052515 (2013)), and the magic wavelength around 1066 nm for the $2\,^3S \to 3\,^3P$ transition can be expected for precision measurement to determine the ratio of transition matrix elements $(2\,^3S \to 2\,^3P) / (3\,^3P\to 6\,^3S)$.