Resonances in the scattering of atoms and molecules

We have demonstrated the resonant control of the elastic scattering cross sections in the vicinity of Feshbach resonances between ^{23}Na^{40}K molecules and ^{40}K atoms by studying the thermalization between them. The elastic scattering cross sections vary by more than 2 orders of magnitude close to the resonance, and can be well described by an asymmetric Fano profile. The parameters that characterize the magnetically tunable s-wave scattering length are determined from the elastic scattering cross sections. The observation of resonantly controlled elastic scattering cross sections opens up the possibility to study strongly interacting atom-molecule mixtures and improve our understanding of the complex atom-molecule Feshbach resonances.We have demonstrated the resonant control of the elastic scattering cross sections in the vicinity of Feshbach resonances between ^{23}Na^{40}K molecules and ^{40}K atoms by studying the thermalization between them. The elastic scattering cross sections vary by more than 2 orders of magnitude close to the resonance, and can be well described by an asymmetric Fano profile. The parameters that characterize the magnetically tunable s-wave scattering length are determined from the elastic scattering cross sections. The observation of resonantly controlled elastic scattering cross sections opens up the possibility to study strongly interacting atom-molecule mixtures and improve our understanding of the complex atom-molecule Feshbach resonances.

arXiv:2203.04584Physical Review LettersJul 13, 202218 citations

Resonances in the Excitation Functions of Atoms

I. P. Zapesochny, О. Б. Шпеник

Jan 1, 19650 citations

THEORY OF RESONANCE SCATTERING ON ATOMIC SYSTEMS

M.V. Kazarnovski, Alexander V. Stepanov

Acta Physica Academiae Scientiarum HungaricaeJan 1, 19622 citations

Broad Feshbach Resonance with a Large Background Scattering Length in a Fermionic Atom-Molecule Mixture

Zhen Su, Tong-Hui Shou, Huan Yang +6 more

We report the observation of a broad magnetic Feshbach resonance with a large background scattering length in an ultracold fermionic mixture of ^{23}Na^{40}K molecules and ^{40}K atoms, with both species prepared in their lowest hyperfine states. The Feshbach resonance is characterized by measuring resonantly enhanced loss rates and elastic scattering cross sections via cross-species thermalization. The large background scattering length can drive the atom-molecule mixture into the hydrodynamic regime when the magnetic field is far from the resonance. We observe that the center-of-mass motions of the atoms and molecules are phase locked and oscillate with a common frequency due to hydrodynamic drag effects. This broad atom-molecule Feshbach resonance with its large background scattering length opens up a new avenue toward studying strongly interacting fermionic gases with mass imbalance.We report the observation of a broad magnetic Feshbach resonance with a large background scattering length in an ultracold fermionic mixture of ^{23}Na^{40}K molecules and ^{40}K atoms, with both species prepared in their lowest hyperfine states. The Feshbach resonance is characterized by measuring resonantly enhanced loss rates and elastic scattering cross sections via cross-species thermalization. The large background scattering length can drive the atom-molecule mixture into the hydrodynamic regime when the magnetic field is far from the resonance. We observe that the center-of-mass motions of the atoms and molecules are phase locked and oscillate with a common frequency due to hydrodynamic drag effects. This broad atom-molecule Feshbach resonance with its large background scattering length opens up a new avenue toward studying strongly interacting fermionic gases with mass imbalance.

arXiv:2511.06772Physical Review LettersNov 6, 20252 citations

Avalanche-mechanism loss at an atom-molecule Efimov resonance

Ming-Guang Hu, Ruth Bloom, Deborah Jin +1 more

The avalanche mechanism has been used to relate Efimov trimer states to certain enhanced atom loss features observed in ultracold-atom-gas experiments. These atom loss features are argued to be a signature of resonant atom-molecule scattering that occurs when an Efimov trimer is degenerate with the atom-molecule scattering threshold. However, observation of these atom loss features has yet to be combined with the direct observation of atom-molecule resonant scattering for any particular atomic species. In addition, recent Monte Carlo simulations were unable to reproduce a narrow loss feature. We experimentally search for enhanced atom loss features near an established scattering resonance between $^{40}\mathrm{K}$ $^{87}\mathrm{Rb}$ Feshbach molecules and $^{87}\mathrm{Rb}$ atoms. Our measurements of both the three-body recombination rate in a gas of $^{40}\mathrm{K}$ and $^{87}\mathrm{Rb}$ atoms and the ratio of the number loss for the two species do not show any broad loss feature and are therefore inconsistent with theoretical predictions that use the avalanche mechanism.The avalanche mechanism has been used to relate Efimov trimer states to certain enhanced atom loss features observed in ultracold-atom-gas experiments. These atom loss features are argued to be a signature of resonant atom-molecule scattering that occurs when an Efimov trimer is degenerate with the atom-molecule scattering threshold. However, observation of these atom loss features has yet to be combined with the direct observation of atom-molecule resonant scattering for any particular atomic species. In addition, recent Monte Carlo simulations were unable to reproduce a narrow loss feature. We experimentally search for enhanced atom loss features near an established scattering resonance between $^{40}\mathrm{K}$ $^{87}\mathrm{Rb}$ Feshbach molecules and $^{87}\mathrm{Rb}$ atoms. Our measurements of both the three-body recombination rate in a gas of $^{40}\mathrm{K}$ and $^{87}\mathrm{Rb}$ atoms and the ratio of the number loss for the two species do not show any broad loss feature and are therefore inconsistent with theoretical predictions that use the avalanche mechanism.

arXiv:1405.4915Physical Review AJul 18, 201429 citations

Scattering and Resonances: Classical and Quantum Dynamics

Pierre Gaspard

Elsevier eBooksJan 1, 199312 citations

^{40}\mathrm{K}

^{87}\mathrm{Rb}

Feshbach molecules and

^{87}\mathrm{Rb}

atoms. Our measurements of both the three-body recombination rate in a gas of

^{40}\mathrm{K}

and

^{87}\mathrm{Rb}

atoms and the ratio of the number loss for the two species do not show any broad loss feature and are therefore inconsistent with theoretical predictions that use the avalanche mechanism.