Jean-François Wyart

Anisotropic optical trapping of ultracold erbium atoms

Ultracold atoms confined in a dipole trap are submitted to a potential whose depth is proportional to the real part of their dynamic dipole polarizability. The atoms also experience photon scattering whose rate is proportional to the imaginary part of their dynamic dipole polarizability. In this article we calculate the complex dynamic dipole polarizability of ground-state erbium, a rare-earth atom that was recently Bose-condensed. The polarizability is calculated with the sum-over-state formula inherent to second-order perturbation theory. The summation is performed on transition energies and transition dipole moments from ground-state erbium, which are computed using the Racah-Slater least-square fitting procedure provided by the Cowan codes. This allows us to predict 9 unobserved odd-parity energy levels of total angular momentum J=5, 6 and 7, in the range 25000-31000 cm-1 above the ground state. Regarding the trapping potential, we find that ground-state erbium essentially behaves like a spherically-symmetric atom, in spite of its large electronic angular momentum. We also find a mostly isotropic van der Waals interaction between two ground-state erbium atoms, characterized by a coefficient C_6^{iso}=1760 a.u.. On the contrary, the photon-scattering rate shows a pronounced anisotropy, since it strongly depends on the polarization of the trapping light.

Anisotropic optical trapping as a manifestation of the complex electronic structure of ultracold lanthanide atoms: The example of holmium

The efficiency of optical trapping is determined by the atomic dynamic dipole polarizability, whose real and imaginary parts are associated with the potential energy and photon-scattering rate respectively. In this article we develop a formalism to calculate analytically the real and imaginary parts of the scalar, vector and tensor polarizabilities of lanthanide atoms. We assume that the sum-over-state formula only comprises transitions involving electrons in the valence orbitals like

Proposal for laser cooling of rare-earth ions

6s

Collisional optical-field ionization soft x-ray lasers

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Demonstration of two-color transient pumping in Ni-like silver at 13.9 nm and 16.1 nm: new progress in applications of x-ray lasers

5d

Progress on collisionally pumped optical-field-ionization soft X-ray lasers

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Advances in collisionally pumped optical-field-ionization soft x-ray lasers

6p

Two-color transient pumping in Ni-like silver at 13.9 and 16.1 nm

or

Ultracold Rare-Earth Magnetic Atoms with an Electric Dipole Moment

7s

Anisotropic polarizability of erbium atoms

, while transitions involving