Event Details

Lanthanides have a special place in field of quantum simulations with cold atom due to their unique properties, such as large orbital momentum and large magnetic momentum in the ground state. Large orbital momentum in ground state leads to easily tunable interactions between cold atoms via low-field Fano-Feshbach resonances, while large magnetic moment leads to relatively strong dipole-dipole interactions. We report on observation of low-field Fano-Feshbach resonances in ultra-cold polarized gas of thulium atoms. Two classes of resonances were observed: rising with temperature d-resonances and having opposite behavior - s-resonances, both shifting their position with temperature much like it been predicted previously. Since thulium atom has only one hole at f-shell the resonances are much less dense then in a case of Erbium and Dysprosium. By carefully examine width dependence of the atomic temperature near the Fano-Feshabach resonance we were able to determine, that average scattering length of the thulium atom is positive and found magnetic field corresponding to zero crossing for the scattering length. Finally, we founs, that statitics of Feshbach resonances changes drastically with temperature of the atomic gas. Been random at low temperatures resonances spacing became chaotic ones d-resonances appear in the spectrum. This transition type of behavior was not observed in other atomic species

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