Physical Review A

Enhanced light-assisted-collision rate via excitation to the long-lived 5S1/2 - 5D5/2 molecular potential in an Rb85 magneto-optical trap

Truman Wilson, Jacob Roberts

Published Mar 25, 2011• 0 citations

Abstract

We report measurements of a significant increase in the two-body loss rate in an $^{85}\mathrm{Rb}$ magneto-optic trap (MOT) caused by the addition of light resonant with the $5{P}_{3/2}$-to-$5{D}_{5/2}$ transition (776 nm) in Rb. Exposure to the additional light resulted in up to a factor of 5 decrease in the steady-state number of atoms in the MOT. This loss is attributed to more than an order of magnitude increase in the light-assisted collision rate brought about by the 776-nm light. By measuring the intensity dependence of the loss rate, the loss channel was identified to be the relatively long-lived $5{S}_{1/2}$-$5{D}_{5/2}$ molecular potential.

DOI: 10.1103/physreva.83.033419

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Physical Review A

Enhanced light-assisted-collision rate via excitation to the long-lived 5S1/2 - 5D5/2 molecular potential in an Rb85 magneto-optical trap

Truman Wilson, Jacob Roberts

Published Mar 25, 2011• 0 citations

Publisher

Abstract

We report measurements of a significant increase in the two-body loss rate in an

^{85}\mathrm{Rb}

magneto-optic trap (MOT) caused by the addition of light resonant with the

5{P}_{3/2}

-to-

5{D}_{5/2}

transition (776 nm) in Rb. Exposure to the additional light resulted in up to a factor of 5 decrease in the steady-state number of atoms in the MOT. This loss is attributed to more than an order of magnitude increase in the light-assisted collision rate brought about by the 776-nm light. By measuring the intensity dependence of the loss rate, the loss channel was identified to be the relatively long-lived

5{S}_{1/2}

5{D}_{5/2}

molecular potential.

DOI: 10.1103/physreva.83.033419

Related papers

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I. S. Cojocaru, Sergey Pyatchenkov, Stepan Snigirev +12 more

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Bulletin of the American Physical SocietyMay 1, 19930 citations

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Chetan Vishwakarma, Kushal Patel, Jay Mangaonkar +3 more

Collisions with background atoms are known to induce a significant shift in the frequency of state-of-the-art optical atomic clocks and contribute to state decoherence in cold atom experiments. The effects of these collisions can be quantified by measuring their cross sections. We experimentally measured the collision cross section between $^{88}$ Sr $-$ N $_{2}$ in a Magneto-Optical Trap (MOT). The measurement was carried out by monitoring the atom number loss rate as a function of background pressure of N $_{2}$ and the cross section thus obtained was 8.1(4) $\times 10^{-18}$ m $^{2}$ . The measured collision cross section has been utilized for the determination of C $_{6}$ coefficient of the ground state ( ${^1S}_0$ ) of $^{88}$ Sr atom, which can be useful to estimate the relative frequency shift in the clock transition. We also estimate the loss rate induced by the combined effect of the decay of atoms in the long-lived ${^3P}_0$ state and temperature-induced atomic losses from the capture volume of the MOT. We find that the contribution due to the latter is dominant in comparison to the other atomic loss channels and must be included in the studies that rely on the total loss rate measurement.Collisions with background atoms are known to induce a significant shift in the frequency of state-of-the-art optical atomic clocks and contribute to state decoherence in cold atom experiments. The effects of these collisions can be quantified by measuring their cross sections. We experimentally measured the collision cross section between $^{88}$Sr$-$N$_{2}$ in a Magneto-Optical Trap (MOT). The measurement was carried out by monitoring the atom number loss rate as a function of background pressure of N$_{2}$ and the cross section thus obtained was 8.1(4)$\times 10^{-18}$ m$^{2}$. The measured collision cross section has been utilized for the determination of C$_{6}$ coefficient of the ground state (${^1S}_0$) of $^{88}$Sr atom, which can be useful to estimate the relative frequency shift in the clock transition. We also estimate the loss rate induced by the combined effect of the decay of atoms in the long-lived ${^3P}_0$ state and temperature-induced atomic losses from the capture volume of the MOT. We find that the contribution due to the latter is dominant in comparison to the other atomic loss channels and must be included in the studies that rely on the total loss rate measurement.

arXiv:1905.03202May 8, 20191 citation

We report measurements of a significant increase in the two-body loss rate in an

^{85}\mathrm{Rb}

magneto-optic trap (MOT) caused by the addition of light resonant with the

5{P}_{3/2}

-to-

5{D}_{5/2}

5{S}_{1/2}

5{D}_{5/2}

molecular potential.

We studied light-assisted collisions of Tm atoms in a magneto-optical trap (MOT), working on a weak cooling transition at 530.7 nm [

4{f}^{13}(^{2}F^{o})6{s}^{2},\phantom{\rule{0.16em}{0ex}}J=7/2,\phantom{\rule{0.16em}{0ex}}F=4

4{f}^{12}(^{3}H_{6})5{d}_{5/2}6{s}^{2},\phantom{\rule{0.16em}{0ex}}J=9/2,\phantom{\rule{0.16em}{0ex}}F=5

]. We observed a strong influence from radiation trapping and light-assisted collisions on the dynamics of this trap. We carefully separated these two contributions and measured the binary loss rate constant at different laser powers and detuning frequencies near the cooling transition. Analyzing losses from the MOT, we found the light-assisted inelastic binary loss rate constant to reach values of up to $\ensuremath{\beta}={10}^{\ensuremath{-}9}\phantom{\rule{0.16em}{0ex}}\mathrm{c}{\mathrm{m}}^{3}/\mathrm{s}$ and gave the upper bound on a branching ratio $k<0.8\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$ for the 530.7 nm transition.

We have studied heteronuclear and homonuclear excited-state--ground-state collisions by loading both

^{85}\mathrm{Rb}

and

^{87}\mathrm{Rb}

into a far off resonant trap (FORT). Because of the relatively weak confinement of the FORT, we expect the hyperfine structure of the different isotopes to play a crucial role in the collision rates. This dependence on hyperfine structure allows us to measure collisions associated with long-range interatomic potentials of different structures, such as long and short ranged; or such as purely attractive, purely repulsive, or mixed attractive and repulsive. We observe significantly different loss rates for different excited-state potentials. Additionally, we observe that some collisional channels' loss rates are saturated at our operating intensities

(15\phantom{\rule{0.3em}{0ex}}\mathrm{mW}∕{\mathrm{cm}}^{2})

. These losses are important limitations in loading dual isotope optical traps.

We have investigated trap loss in a dual-species magneto-optical trap (MOT) comprised of

^{85}\mathrm{Rb}

and metastable

^{40}\mathrm{Ar}

. We measure the trap loss rate coefficients for each species due to the presence of the other as a function of trap light intensity. We clearly identify both Penning ionization of Rb by

{\mathrm{Ar}}^{*}

and associative ionization to form the molecular ion

\mathrm{Rb}{\mathrm{Ar}}^{+}

as two of the trap loss channels. We have also measured the trap loss rate coefficient for the

{\mathrm{Ar}}^{*}

MOT alone and observe production of

{\mathrm{Ar}}^{+}

and

\mathrm{Ar}_{2}{}^{+}

ions.

^{88}

-

_{2}

in a Magneto-Optical Trap (MOT). The measurement was carried out by monitoring the atom number loss rate as a function of background pressure of N

_{2}

and the cross section thus obtained was 8.1(4)

\times 10^{-18}

^{2}

. The measured collision cross section has been utilized for the determination of C

_{6}

coefficient of the ground state (

{^1S}_0

) of

^{88}

Sr atom, which can be useful to estimate the relative frequency shift in the clock transition. We also estimate the loss rate induced by the combined effect of the decay of atoms in the long-lived

{^3P}_0

state and temperature-induced atomic losses from the capture volume of the MOT. We find that the contribution due to the latter is dominant in comparison to the other atomic loss channels and must be included in the studies that rely on the total loss rate measurement.