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arXiv:2105.10944 · Physical Review A

Dominant scattering channel induced by two-body collision of D -band atoms in a triangular optical lattice

Xinxin Guo, Zhongcheng Yu, Peng Peng, Guoling Yin, Shengjie Jin, Xuzong Chen, Xiaoji Zhou

Published Sep 30, 2021• 9 citations
arXivHTMLPDF

Abstract

The mechanism of atomic collisions in excited bands plays an important role in both the atomic dynamics in high bands of optical lattices and the simulation of condensed matter physics. Atoms distributed in an excited band of an optical lattice can collide and decay to other bands through different scattering channels. In the excited bands of a one-dimensional lattice there is no significant difference between the cross sections to different scattering channels, due to the sameness of all of the geometrical couplings. Here, we investigate the collisional scattering channels for atoms in the excited bands of a triangular optical lattice and demonstrate a dominant scattering channel in the experiment. A shortcut method is utilized to load Bose-Einstein condensate of $^{87}\mathrm{Rb}$ atoms into the $\mathrm{\ensuremath{\Gamma}}$ point of the first $D$ band with zero quasimomentum in the triangular optical lattice. After some evolution time, the number of atoms scattering into the $S$ band induced by two-body collisions is around four times the number that scatter into the second most populated band. Our numerical calculation shows that the $ss$ scattering channel is dominant, which is roughly consistent with the experimental measurement. The appearance of dominant scattering channels in a triangular optical lattice is owing to nonorthogonal lattice vectors. This work is helpful for the research on many-body systems and directional enhancement in optical lattices.

DOI
10.1103/physreva.104.033326

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The mechanism of atomic collisions in excited bands plays an important role in both the atomic dynamics in high bands of optical lattices and the simulation of condensed matter physics. Atoms distributed in an excited band of an optical lattice can collide and decay to other bands through different scattering channels. In the excited bands of a one-dimensional lattice there is no significant difference between the cross sections to different scattering channels, due to the sameness of all of the geometrical couplings. Here, we investigate the collisional scattering channels for atoms in the excited bands of a triangular optical lattice and demonstrate a dominant scattering channel in the experiment. A shortcut method is utilized to load Bose-Einstein condensate of 87Rb^{87}\mathrm{Rb}87Rb atoms into the \ensuremathΓ\mathrm{\ensuremath{\Gamma}}\ensuremathΓ point of the first DDD band with zero quasimomentum in the triangular optical lattice. After some evolution time, the number of atoms scattering into the SSS band induced by two-body collisions is around four times the number that scatter into the second most populated band. Our numerical calculation shows that the ssssss scattering channel is dominant, which is roughly consistent with the experimental measurement. The appearance of dominant scattering channels in a triangular optical lattice is owing to nonorthogonal lattice vectors. This work is helpful for the research on many-body systems and directional enhancement in optical lattices.
The excited bands in optical lattices manifest an important tool for studying quantum simulation and many-body physics, making it crucial to measure high-band scattering dynamics under strong interactions. This work investigates both experimentally and theoretically the collisional scattering of Li 2 6 molecular Bose-Einstein condensate in the D band of a one-dimensional optical lattice, with interaction strength directly tunable via magnetic Feshbach resonance. We find a clear dependence of the D -band lifetimes on the interaction strength within the strongly interacting regime, which arises from the fact that the scattering cross section is proportional to the square of the scattering length. The maximum lifetime versus lattice depth is measured to reveal the effects of interactions. We also investigate the scattering channels of D -band molecules under different interaction levels and develop a reliable two-body scattering rate equation. This work provides insight into the interplay between interaction and the collisional scattering of high-band bosons in optical lattices, paving the way for research into strong correlation effects in high-band lattice systems.
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