arXiv:1404.4826 · Physical Review A

Ultracold mixtures of metastable He and Rb: Scattering lengths fromab initiocalculations and thermalization measurements

Steven Knoop, Piotr Szymon Żuchowski, Dariusz Kędziera, Ł. M. Mentel, Mariusz Puchalski, Hari Prasad Mishra, Adonis Silva Flores, W. Vassen

Published Aug 13, 2014• 15 citations

arXiv HTML PDF

Abstract

State-of-the-art $a\phantom{\rule{0}{0ex}}b$ $i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}o$ quantum calculations and thermalization measurements have been made on an ultracold mixture of metastable helium and rubidium in a magnetic trap, allowing for the first time to quantitatively predict the scattering length for a system containing a heavy, many-electron atom.

DOI: 10.1103/physreva.90.022709

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arXiv:1404.4826 · Physical Review A

Ultracold mixtures of metastable He and Rb: Scattering lengths fromab initiocalculations and thermalization measurements

Steven Knoop, Piotr Szymon Żuchowski, Dariusz Kędziera, Ł. M. Mentel, Mariusz Puchalski, Hari Prasad Mishra, Adonis Silva Flores, W. Vassen

Published Aug 13, 2014• 15 citations

arXiv HTML PDF

Abstract

State-of-the-art

a\phantom{\rule{0}{0ex}}b

i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}o

quantum calculations and thermalization measurements have been made on an ultracold mixture of metastable helium and rubidium in a magnetic trap, allowing for the first time to quantitatively predict the scattering length for a system containing a heavy, many-electron atom.

DOI: 10.1103/physreva.90.022709

Related papers

Ultracold thermalization of Li7 and Rb87

C. Marzok, Benjamin Deh, Ph. W. Courteille +1 more

We report on measurements of cross-species thermalization inside a magnetically trapped spin-polarized mixture of $^{87}\mathrm{Rb}$ and $^{7}\mathrm{Li}$ atoms with both atoms in their respective low-field-seeking magnetic substates $\ensuremath{\mid}F=2,{m}_{F}=2⟩$. Measurement of the thermalization velocity in the ultracold regime below $10\phantom{\rule{0.3em}{0ex}}\mathrm{\ensuremath{\mu}}\mathrm{K}$ allows for the derivation of the absolute value of the pure triplet $s$ -wave scattering length governing the interaction. We find $\ensuremath{\mid}{a}_{7,87}\ensuremath{\mid}=(59\ifmmode\pm\else\textpm\fi{}19){a}_{\mathrm{B}}$. We propose to study both species in the condensed regime to derive the sign of ${a}_{7,87}$ . In this context, we present numerical solutions to the coupled Gross-Pitaevskii equation based on the hypothesis of a positive sign. According to the simulations, phase separation of the Li and Rb $\ensuremath{\mid}2,2⟩$ clouds occurs along with a mean-field stabilization allowing for larger atom numbers of condensed $^{7}\mathrm{Li}$ atoms before collapse sets in. Observation of this mean-field stabilization would directly fix the sign of ${a}_{7,87}$ . We discuss our results in the light of this proposal.We report on measurements of cross-species thermalization inside a magnetically trapped spin-polarized mixture of $^{87}\mathrm{Rb}$ and $^{7}\mathrm{Li}$ atoms with both atoms in their respective low-field-seeking magnetic substates $\ensuremath{\mid}F=2,{m}_{F}=2⟩$. Measurement of the thermalization velocity in the ultracold regime below $10\phantom{\rule{0.3em}{0ex}}\mathrm{\ensuremath{\mu}}\mathrm{K}$ allows for the derivation of the absolute value of the pure triplet $s$-wave scattering length governing the interaction. We find $\ensuremath{\mid}{a}_{7,87}\ensuremath{\mid}=(59\ifmmode\pm\else\textpm\fi{}19){a}_{\mathrm{B}}$. We propose to study both species in the condensed regime to derive the sign of ${a}_{7,87}$. In this context, we present numerical solutions to the coupled Gross-Pitaevskii equation based on the hypothesis of a positive sign. According to the simulations, phase separation of the Li and Rb $\ensuremath{\mid}2,2⟩$ clouds occurs along with a mean-field stabilization allowing for larger atom numbers of condensed $^{7}\mathrm{Li}$ atoms before collapse sets in. Observation of this mean-field stabilization would directly fix the sign of ${a}_{7,87}$. We discuss our results in the light of this proposal.

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J. M. McNamara, R. J. W. Stas, W. Hogervorst +1 more

We have investigated cold ionizing heteronuclear collisions in dilute mixtures of metastable $(2\phantom{\rule{0.2em}{0ex}}^{3}S_{1})$ $^{3}\mathrm{He}$ and $^{4}\mathrm{He}$ atoms, extending our previous work on the analogous homonuclear collisions [R. J. W. Stas et al., Phys. Rev. A 73, 032713 (2006)]. A simple theoretical model of such collisions enables us to calculate the heteronuclear ionization rate coefficient, for our quasiunpolarized gas, in the absence of resonant light $(T=1.2\phantom{\rule{0.2em}{0ex}}\mathrm{mK})$ : ${K}_{34}^{(\mathrm{th})}=2.4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{3}∕\mathrm{s}$. This calculation is supported by a measurement of ${K}_{34}$ using magneto-optically trapped mixtures containing about $1\ifmmode\times\else\texttimes\fi{}{10}^{8}$ atoms of each species, ${K}_{34}^{(\mathrm{exp})}=2.5(8)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{3}∕\mathrm{s}$. Theory and experiment show good agreement.We have investigated cold ionizing heteronuclear collisions in dilute mixtures of metastable $(2\phantom{\rule{0.2em}{0ex}}^{3}S_{1})$ $^{3}\mathrm{He}$ and $^{4}\mathrm{He}$ atoms, extending our previous work on the analogous homonuclear collisions [R. J. W. Stas et al., Phys. Rev. A 73, 032713 (2006)]. A simple theoretical model of such collisions enables us to calculate the heteronuclear ionization rate coefficient, for our quasiunpolarized gas, in the absence of resonant light $(T=1.2\phantom{\rule{0.2em}{0ex}}\mathrm{mK})$: ${K}_{34}^{(\mathrm{th})}=2.4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{3}∕\mathrm{s}$. This calculation is supported by a measurement of ${K}_{34}$ using magneto-optically trapped mixtures containing about $1\ifmmode\times\else\texttimes\fi{}{10}^{8}$ atoms of each species, ${K}_{34}^{(\mathrm{exp})}=2.5(8)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{3}∕\mathrm{s}$. Theory and experiment show good agreement.

arXiv:physics/0701194Physical Review AJun 29, 200713 citations

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K. G. H. Baldwin, L. J. Uhlmann, R. G. Dall +2 more

Conference on Lasers and Electro-OpticsJan 1, 20040 citations

We report on measurements of cross-species thermalization inside a magnetically trapped spin-polarized mixture of

^{87}\mathrm{Rb}

and

^{7}\mathrm{Li}

atoms with both atoms in their respective low-field-seeking magnetic substates $\ensuremath{\mid}F=2,{m}_{F}=2⟩$. Measurement of the thermalization velocity in the ultracold regime below $10\phantom{\rule{0.3em}{0ex}}\mathrm{\ensuremath{\mu}}\mathrm{K}$ allows for the derivation of the absolute value of the pure triplet

s

-wave scattering length governing the interaction. We find $\ensuremath{\mid}{a}_{7,87}\ensuremath{\mid}=(59\ifmmode\pm\else\textpm\fi{}19){a}_{\mathrm{B}}$. We propose to study both species in the condensed regime to derive the sign of

{a}_{7,87}

. In this context, we present numerical solutions to the coupled Gross-Pitaevskii equation based on the hypothesis of a positive sign. According to the simulations, phase separation of the Li and Rb $\ensuremath{\mid}2,2⟩$ clouds occurs along with a mean-field stabilization allowing for larger atom numbers of condensed

^{7}\mathrm{Li}

atoms before collapse sets in. Observation of this mean-field stabilization would directly fix the sign of

{a}_{7,87}

. We discuss our results in the light of this proposal.

2{}^{3}S

helium atoms as a function of the uncertainty in these potentials. These scattering lengths are used to calculate experimentally observable scattering lengths, elastic cross sections, and inelastic rates for any combination of states of the colliding atoms, at temperatures where the Wigner threshold approximation is valid.

^{4}\mathrm{He}^{*}+^{4}\mathrm{He}^{*}

and fermionic

^{3}\mathrm{He}^{*}+^{3}\mathrm{He}^{*}

systems, and heteronuclear collisions of the mixed

^{3}\mathrm{He}^{*}+^{4}\mathrm{He}^{*}

system, are investigated over the temperature range 1 $\ensuremath{\mu}\mathrm{K}$ to 1 K. Carefully constructed Born-Oppenheimer molecular potentials are used to describe the electrostatic interaction between the colliding atoms, and complex optical potentials to represent loss through ionization from the ${}^{1,3}\mathrm{\ensuremath{\Sigma}}$ states. Magnetic spin-dipole-mediated transitions from the ${}^{5}\mathrm{\ensuremath{\Sigma}}$ state are included and results reported for spin-polarized and unpolarized systems. Comparisons are made with experimental results, previous semiclassical models, and a perturbed single-channel model.

We compute the scattering properties of rubidium atoms at ultracold temperatures, placing special emphasis on the radioactive isotopes

{}^{82}\mathrm{Rb}{,}^{83}\mathrm{Rb}{,}^{84}\mathrm{Rb},

and

{}^{86}\mathrm{Rb}.

In combination with the more ``conventional'' isotope

{}^{87}\mathrm{Rb},

these species yield a wide variety of scattering behavior, with consequences for creating mixtures of Fermi-Fermi, Fermi-Bose, and Bose-Bose gases. In each of these mixtures we find at least one case where the interspecies scattering lengths can be tuned using an external magnetic field. These results should greatly broaden the prospects for quantum degenerate gases in future experiments.

We have investigated cold ionizing heteronuclear collisions in dilute mixtures of metastable

(2\phantom{\rule{0.2em}{0ex}}^{3}S_{1})

^{3}\mathrm{He}

and

^{4}\mathrm{He}

atoms, extending our previous work on the analogous homonuclear collisions [R. J. W. Stas et al., Phys. Rev. A 73, 032713 (2006)]. A simple theoretical model of such collisions enables us to calculate the heteronuclear ionization rate coefficient, for our quasiunpolarized gas, in the absence of resonant light

(T=1.2\phantom{\rule{0.2em}{0ex}}\mathrm{mK})

: ${K}_{34}^{(\mathrm{th})}=2.4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{3}∕\mathrm{s}$. This calculation is supported by a measurement of

{K}_{34}

using magneto-optically trapped mixtures containing about $1\ifmmode\times\else\texttimes\fi{}{10}^{8}$ atoms of each species, ${K}_{34}^{(\mathrm{exp})}=2.5(8)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{3}∕\mathrm{s}$. Theory and experiment show good agreement.