Tune-out wavelength for the thulium atom near 576 nm

TL;DR

This paper combines theoretical prediction and experimental measurement to identify and refine the tune-out wavelength of thulium atoms near 576 nm, enabling precise control of atomic polarizability for Bose-Einstein condensation.

Contribution

It provides the first combined theoretical and experimental determination of the thulium tune-out wavelength near 576 nm with high precision.

Findings

Measured tune-out wavelength: 575.646 nm in air

Confirmed the zero in polarizability for Tm ground state

Achieved Bose-Einstein condensation at the tune-out wavelength range

Abstract

We report the theoretical prediction and measurement of a tune-out wavelength for the ground state of the thulium atom in a linearly polarized optical dipole trap with a wavelength of approximately 576 nm. The measurements were conducted using a combination of trap frequency and RF loss spectroscopy, thus making it possible to separate the scalar and tensor parts of the total polarizability without measurements in the range of negative total polarizability. The calculated tune-out wavelength is consistent with the measured one of $575.646_{-0.014}^{+0.016}$ nm in air. The existence of the zero in the polarizability for the Tm ground state was confirmed by the trap loss experiment, which also made it possible to refine the tune-out wavelength to $575.646_{-0.004}^{+0.004}$. Despite the presence of an imaginary part of the polarizability at some wavelengths, it was experimentally demonstrated that, with a proper choice of the dipole trap polarization, it was possible to achieve Bose-Einstein condensation of thulium atoms in the range from 575.348 to 575.689 nm, covering the tune-out wavelength.