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arXiv:1510.06992 · Physical Review A

Quantum chaos in ultracold collisions between Yb(1S0) and Yb(3P2)

Dermot G. Green, Christophe L. Vaillant, Matthew D. Frye, Masato Morita, Jeremy M. Hutson

Published Feb 4, 2016• 17 citations
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Abstract

We calculate and analyze Feshbach resonance spectra for ultracold $\mathrm{Yb}({}^{1}{S}_{0})+\mathrm{Yb}({}^{3}{P}_{2})$ collisions as a function of an interatomic potential scaling factor $\ensuremath{\lambda}$ and external magnetic field. We show that, at zero field, the resonances are distributed randomly in $\ensuremath{\lambda}$, but that signatures of quantum chaos emerge as a field is applied. The random zero-field distribution arises from superposition of structured spectra associated with individual total angular momenta. In addition, we show that the resonances with respect to magnetic field in the experimentally accessible range of 400 to 2000 G are chaotically distributed, with strong level repulsion that is characteristic of quantum chaos.

DOI
10.1103/physreva.93.022703

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We calculate and analyze Feshbach resonance spectra for ultracold Yb(1S0)+Yb(3P2)\mathrm{Yb}({}^{1}{S}_{0})+\mathrm{Yb}({}^{3}{P}_{2})Yb(1S0​)+Yb(3P2​) collisions as a function of an interatomic potential scaling factor \ensuremathλ\ensuremath{\lambda}\ensuremathλ and external magnetic field. We show that, at zero field, the resonances are distributed randomly in \ensuremathλ\ensuremath{\lambda}\ensuremathλ, but that signatures of quantum chaos emerge as a field is applied. The random zero-field distribution arises from superposition of structured spectra associated with individual total angular momenta. In addition, we show that the resonances with respect to magnetic field in the experimentally accessible range of 400 to 2000 G are chaotically distributed, with strong level repulsion that is characteristic of quantum chaos.
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Strongly dipolar gases, such as dysprosium, erbium and thulium, exhibit dense Feshbach spectra whose level statistics have been associated with quantum chaos arising from couplings among many molecular channels. Here, we combine a precise calibration of the Feshbach spectrum of 162^{162}162Dy with spectroscopic measurements of the differential magnetic moments of bound states associated with more than 80 resonances between 0 and 30 G. These magnetic moments provide an eigenstate-sensitive probe of the molecular states underlying the resonance spectrum. We find that the level statistics are not uniform: resonances associated with states near the center of the magnetic-moment distribution display enhanced level repulsion, whereas those near the lower edge remain close to Poisson statistics. Our results reveal hidden structure within the chaotic dysprosium Feshbach spectrum and identify molecular-state composition as a key ingredient in the emergence of quantum chaos in strongly dipolar scattering.
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Abstract we report on signatures of classical chaos in ultracold collisions between a trapped ion and a free atom. Using numerical simulations, we show that the scattering dynamics can be highly sensitive to initial conditions for various mass ratios and trapping frequencies, indicating the onset of chaos. We quantify this chaotic dynamics by calculating its fractal dimension. We show that for a trapped 88 Sr + ion and a free 87 Rb atom chaotic dynamic appears under experimentally relevant conditions, and find its characteristic energy scale. The observation of classical chaos in atom-trapped-ion collisions suggests that signatures of quantum chaos might appear, for example, through a Wigner–Dyson distribution of collisional resonances.
We have investigated magnetically tunable Feshbach resonances in ultracold collisions of Rb with Yb in its metastable 3P2{}^{3}{P}_{2}3P2​ and 3P0{}^{3}{P}_{0}3P0​ states, using coupled-channel scattering and bound-state calculations. For the 3P2{}^{3}{P}_{2}3P2​ state, we find sharp resonances when both atoms are in their lowest Zeeman sublevels. However, these resonances are decayed by inelastic processes that produce Yb atoms in 3P1{}^{3}{P}_{1}3P1​ and 3P0{}^{3}{P}_{0}3P0​ states. The molecules that might be produced by magnetoassociation at the 3P2{}^{3}{P}_{2}3P2​ thresholds can decay by similar pathways and would have lifetimes no more than a few microseconds. For the 3P0{}^{3}{P}_{0}3P0​ state, by contrast, there are resonances that are promising for magnetoassociation. There are resonances due to both rotating and nonrotating molecular states that are significantly stronger than the analogous resonances for Yb(1S\mathrm{Yb}{(}^{1}SYb(1S). The ones due to rotating states are denser in magnetic field; in contrast to Yb(1S\mathrm{Yb}{(}^{1}SYb(1S), they exist even for bosonic isotopes of Yb(3P0\mathrm{Yb}{(}^{3}{P}_{0}Yb(3P0​).