Physical Review A

Cooling and trapping of Rb85 atoms in the ground hyperfine F=2 state

Vibhuti Bhushan Tiwari, Sunita Singh, H. S. Rawat, S. C. Mehendale

Published Dec 29, 2008• 20 citations

Abstract

We report cooling and trapping of $^{85}\mathrm{Rb}$ atoms in the lower hyperfine level $F=2$ of the $5\phantom{\rule{0.3em}{0ex}}^{2}S_{1∕2}$ ground state in a magneto-optical trap. A maximum of $\ensuremath{\sim}6\ifmmode\times\else\texttimes\fi{}{10}^{6}$ atoms could be trapped using trap laser frequency red detuned by $12\phantom{\rule{0.3em}{0ex}}\mathrm{MHz}$ from the $F=2\ensuremath{\rightarrow}{F}^{\ensuremath{'}}=1$ cycling transition. The loading behavior of the trap in terms of loading rate, collisional loss rate, number and density of trapped atoms was studied as a function of trap laser intensity.

DOI: 10.1103/physreva.78.063421

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Characteristics of unconventional Rb magneto-optical traps

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Physical Review A

Cooling and trapping of Rb85 atoms in the ground hyperfine F=2 state

Vibhuti Bhushan Tiwari, Sunita Singh, H. S. Rawat, S. C. Mehendale

Published Dec 29, 2008• 20 citations

Publisher

Abstract

We report cooling and trapping of

^{85}\mathrm{Rb}

atoms in the lower hyperfine level

F=2

of the

5\phantom{\rule{0.3em}{0ex}}^{2}S_{1∕2}

ground state in a magneto-optical trap. A maximum of

\ensuremath{\sim}6\ifmmode\times\else\texttimes\fi{}{10}^{6}

atoms could be trapped using trap laser frequency red detuned by

12\phantom{\rule{0.3em}{0ex}}\mathrm{MHz}

from the

F=2\ensuremath{\rightarrow}{F}^{\ensuremath{'}}=1

cycling transition. The loading behavior of the trap in terms of loading rate, collisional loss rate, number and density of trapped atoms was studied as a function of trap laser intensity.

DOI: 10.1103/physreva.78.063421

Related papers

Magneto-optical trapping of holmium atoms

Jinlu Miao, James Hostetter, Georgios Stratis +1 more

We demonstrate sub-Doppler laser cooling and magneto-optical trapping of the rare earth element Holmium. Atoms are loaded from an atomic beam source and captured in six-beam $σ_+ - σ_-$ molasses using a strong $J=15/2 \leftrightarrow J=17/2$ cycling transition at $λ=410.5 \rm nm$ . Due to the small difference in hyperfine splittings and Landé $g$ -factors in the lower and upper levels of the cooling transition the MOT is self-repumped without additional repump light, and deep sub-Doppler cooling is achieved with the magnetic trap turned on. We measure the leakage out of the cycling transition to metastable states and find a branching ratio $\sim 10^{-5}$ which is adequate for state resolved measurements on hyperfine encoded qubits.We demonstrate sub-Doppler laser cooling and magneto-optical trapping of the rare earth element Holmium. Atoms are loaded from an atomic beam source and captured in six-beam $σ_+ - σ_-$ molasses using a strong $J=15/2 \leftrightarrow J=17/2$ cycling transition at $λ=410.5 \rm nm$. Due to the small difference in hyperfine splittings and Landé $g$-factors in the lower and upper levels of the cooling transition the MOT is self-repumped without additional repump light, and deep sub-Doppler cooling is achieved with the magnetic trap turned on. We measure the leakage out of the cycling transition to metastable states and find a branching ratio $\sim 10^{-5}$ which is adequate for state resolved measurements on hyperfine encoded qubits.

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Physical Review LettersAug 10, 1992122 citations

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We report on measurements of trap-loss collisions between ultracold Rb atoms that are confined in a magneto-optical trap. Both isotopes, ${}^{85}\mathrm{Rb}$ and ${}^{87}\mathrm{Rb},$ have been studied over a wide range of trap laser intensities and detunings. The trap-loss collisional rate constant exhibits variations over three orders of magnitude. At low intensities and/or large detunings, the trap loss is dominated by ground-state hyperfine-changing collisions, while at high intensities and small detunings, collisions involving excited atoms are more important. We see significant differences between the isotopes in both regimes. At large detunings, the ability of the trap to recapture products of a hyperfine-changing collision is significantly diminished. This finding is supported by our numerical simulations of the recapture process. The trap loss rates due to collisions with room-temperature background gas have also been measured. A surprisingly large increase in this rate is seen when the confining power of the trap is reduced.We report on measurements of trap-loss collisions between ultracold Rb atoms that are confined in a magneto-optical trap. Both isotopes, ${}^{85}\mathrm{Rb}$ and ${}^{87}\mathrm{Rb},$ have been studied over a wide range of trap laser intensities and detunings. The trap-loss collisional rate constant exhibits variations over three orders of magnitude. At low intensities and/or large detunings, the trap loss is dominated by ground-state hyperfine-changing collisions, while at high intensities and small detunings, collisions involving excited atoms are more important. We see significant differences between the isotopes in both regimes. At large detunings, the ability of the trap to recapture products of a hyperfine-changing collision is significantly diminished. This finding is supported by our numerical simulations of the recapture process. The trap loss rates due to collisions with room-temperature background gas have also been measured. A surprisingly large increase in this rate is seen when the confining power of the trap is reduced.

Physical Review ANov 1, 199757 citations

Reduction of light-assisted collisional loss rate from a low-pressure vapor-cell trap

Michael H. Anderson, Wolfgang H. Petrich, J. R. Ensher +1 more

We have demonstrated an order of magnitude increase in the number and in the lifetime of magneto-optically trapped $^{87}\mathrm{Rb}$ atoms collected from a low-pressure vapor. The improvement results from the reduction of light-assisted collision losses and is achieved by shelving the atomic population into the lower hyperfine ground state. Large fractional populations of the lower hyperfine ground state have been obtained by blocking the hyperfine repumping light in the region of the trapped atoms and by application of laser light that optically pumps the atoms into that state. We have observed trap lifetimes in excess of 700 s at our highest vacuum levels. At the rubidium pressure that maximizes the product of the number and lifetime of trapped atoms we observe a lifetime of 240 s with 5\ifmmode\times\else\texttimes\fi{} ${10}^{7}$ trapped atoms, under conditions for which an ordinary magneto-optical trap has a lifetime of only 14 s with 3\ifmmode\times\else\texttimes\fi{} ${10}^{6}$ atoms.We have demonstrated an order of magnitude increase in the number and in the lifetime of magneto-optically trapped $^{87}\mathrm{Rb}$ atoms collected from a low-pressure vapor. The improvement results from the reduction of light-assisted collision losses and is achieved by shelving the atomic population into the lower hyperfine ground state. Large fractional populations of the lower hyperfine ground state have been obtained by blocking the hyperfine repumping light in the region of the trapped atoms and by application of laser light that optically pumps the atoms into that state. We have observed trap lifetimes in excess of 700 s at our highest vacuum levels. At the rubidium pressure that maximizes the product of the number and lifetime of trapped atoms we observe a lifetime of 240 s with 5\ifmmode\times\else\texttimes\fi{}${10}^{7}$ trapped atoms, under conditions for which an ordinary magneto-optical trap has a lifetime of only 14 s with 3\ifmmode\times\else\texttimes\fi{}${10}^{6}$ atoms.

Physical Review ANov 1, 199487 citations

Characteristics of unconventional Rb magneto-optical traps

K. N. Jarvis, B. E. Sauer, Michael R. Tarbutt

We study several magneto-optical trapping configurations in $^{87}\mathrm{Rb}$ . These unconventional MOTs all use type-II transitions, where the angular momentum of the ground state is greater than or equal to that of the excited state. Some use red-detuned light, and others blue-detuned light. The properties of these MOTs are strongly influenced by the balance between opposing Doppler and Sisyphus forces, and vary widely from one configuration to another. In the blue-detuned MOT, Sisyphus cooling dominates over Doppler heating for all relevant speeds and magnetic fields. We measure the capture velocity of this MOT as a function of intensity and detuning, finding a maximum of $3.8\ifmmode\pm\else\textpm\fi{}0.1$ m/s. Atomic densities are particularly high in the blue-detuned MOT, and its lifetime is limited by collisions between the trapped atoms. We present measurements of the loss rate due to these ultracold collisions as a function of laser intensity and detuning. In the red-detuned MOTs, Sisyphus heating dominates at low speeds and Doppler cooling at higher speeds. Consequently, temperatures in the red-detuned MOTs are up to a thousand times higher than in the blue-detuned MOTs. One MOT forms large ring structures, with no density at the center, showing how atoms driven towards a non-zero equilibrium speed remain trapped by orbiting around the center. Another MOT demonstrates that magnetic mixing of the excited-state hyperfine levels can be an important mechanism in type-II MOTs.We study several magneto-optical trapping configurations in $^{87}\mathrm{Rb}$. These unconventional MOTs all use type-II transitions, where the angular momentum of the ground state is greater than or equal to that of the excited state. Some use red-detuned light, and others blue-detuned light. The properties of these MOTs are strongly influenced by the balance between opposing Doppler and Sisyphus forces, and vary widely from one configuration to another. In the blue-detuned MOT, Sisyphus cooling dominates over Doppler heating for all relevant speeds and magnetic fields. We measure the capture velocity of this MOT as a function of intensity and detuning, finding a maximum of $3.8\ifmmode\pm\else\textpm\fi{}0.1$ m/s. Atomic densities are particularly high in the blue-detuned MOT, and its lifetime is limited by collisions between the trapped atoms. We present measurements of the loss rate due to these ultracold collisions as a function of laser intensity and detuning. In the red-detuned MOTs, Sisyphus heating dominates at low speeds and Doppler cooling at higher speeds. Consequently, temperatures in the red-detuned MOTs are up to a thousand times higher than in the blue-detuned MOTs. One MOT forms large ring structures, with no density at the center, showing how atoms driven towards a non-zero equilibrium speed remain trapped by orbiting around the center. Another MOT demonstrates that magnetic mixing of the excited-state hyperfine levels can be an important mechanism in type-II MOTs.

arXiv:1807.07655Physical Review AOct 25, 20186 citations

We report cooling and trapping of

^{85}\mathrm{Rb}

atoms in the lower hyperfine level

F=2

of the

5\phantom{\rule{0.3em}{0ex}}^{2}S_{1∕2}

ground state in a magneto-optical trap. A maximum of

\ensuremath{\sim}6\ifmmode\times\else\texttimes\fi{}{10}^{6}

atoms could be trapped using trap laser frequency red detuned by

12\phantom{\rule{0.3em}{0ex}}\mathrm{MHz}

from the

F=2\ensuremath{\rightarrow}{F}^{\ensuremath{'}}=1

cycling transition. The loading behavior of the trap in terms of loading rate, collisional loss rate, number and density of trapped atoms was studied as a function of trap laser intensity.

We demonstrate sub-Doppler laser cooling and magneto-optical trapping of the rare earth element Holmium. Atoms are loaded from an atomic beam source and captured in six-beam

σ_+ - σ_-

molasses using a strong

J=15/2 \leftrightarrow J=17/2

cycling transition at

λ=410.5 \rm nm

. Due to the small difference in hyperfine splittings and Landé

g

-factors in the lower and upper levels of the cooling transition the MOT is self-repumped without additional repump light, and deep sub-Doppler cooling is achieved with the magnetic trap turned on. We measure the leakage out of the cycling transition to metastable states and find a branching ratio

\sim 10^{-5}

which is adequate for state resolved measurements on hyperfine encoded qubits.

Thulium atoms are trapped in a magneto-optical trap using a strong transition at

410

nm with a small branching ratio. We trap up to $7\ifmmode\times\else\texttimes\fi{}{10}^{4}$ atoms at a temperature of

0.8(2)

mK after deceleration in a

40

-cm-long Zeeman slower. Optical leaks from the cooling cycle influence the lifetime of atoms in the magneto-optical trap which varies between

0.3

and

1.5

s in our experiments. The lower limit for the leaking rate from the upper cooling level is measured to be

22(6)

${\mathrm{s}}^{\ensuremath{-}1}$. The repumping laser transferring the atomic population out of the

F=3

hyperfine ground-state sublevel gives a

30%

increase for the lifetime and the number of atoms in the trap.

We report measurements of collisional rate constants for cold Rb atoms held in a magneto-optical trap.

^{85}\mathrm{Rb}

and

^{87}\mathrm{Rb}

display significantly different behavior. At low trap laser intensities, atoms which undergo a hyperfine-changing collision gain sufficient velocity to escape the trap. Since the hyperfine splittings are quite different for the isotopes, the loss rates display a large isotopic dependence in this regime. At higher trap laser intensities, where trap loss is due to inelastic collisions involving excited atoms, a dramatic and unexpected isotopic dependence is seen. Under identical conditions, the loss rate for

^{85}\mathrm{Rb}

is 3.3 times that of

^{87}\mathrm{Rb}

We report on measurements of trap-loss collisions between ultracold Rb atoms that are confined in a magneto-optical trap. Both isotopes,

{}^{85}\mathrm{Rb}

and

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

have been studied over a wide range of trap laser intensities and detunings. The trap-loss collisional rate constant exhibits variations over three orders of magnitude. At low intensities and/or large detunings, the trap loss is dominated by ground-state hyperfine-changing collisions, while at high intensities and small detunings, collisions involving excited atoms are more important. We see significant differences between the isotopes in both regimes. At large detunings, the ability of the trap to recapture products of a hyperfine-changing collision is significantly diminished. This finding is supported by our numerical simulations of the recapture process. The trap loss rates due to collisions with room-temperature background gas have also been measured. A surprisingly large increase in this rate is seen when the confining power of the trap is reduced.

We have demonstrated an order of magnitude increase in the number and in the lifetime of magneto-optically trapped

^{87}\mathrm{Rb}

atoms collected from a low-pressure vapor. The improvement results from the reduction of light-assisted collision losses and is achieved by shelving the atomic population into the lower hyperfine ground state. Large fractional populations of the lower hyperfine ground state have been obtained by blocking the hyperfine repumping light in the region of the trapped atoms and by application of laser light that optically pumps the atoms into that state. We have observed trap lifetimes in excess of 700 s at our highest vacuum levels. At the rubidium pressure that maximizes the product of the number and lifetime of trapped atoms we observe a lifetime of 240 s with 5\ifmmode\times\else\texttimes\fi{}

{10}^{7}

trapped atoms, under conditions for which an ordinary magneto-optical trap has a lifetime of only 14 s with 3\ifmmode\times\else\texttimes\fi{}

{10}^{6}

atoms.

We study several magneto-optical trapping configurations in

^{87}\mathrm{Rb}

. These unconventional MOTs all use type-II transitions, where the angular momentum of the ground state is greater than or equal to that of the excited state. Some use red-detuned light, and others blue-detuned light. The properties of these MOTs are strongly influenced by the balance between opposing Doppler and Sisyphus forces, and vary widely from one configuration to another. In the blue-detuned MOT, Sisyphus cooling dominates over Doppler heating for all relevant speeds and magnetic fields. We measure the capture velocity of this MOT as a function of intensity and detuning, finding a maximum of $3.8\ifmmode\pm\else\textpm\fi{}0.1$ m/s. Atomic densities are particularly high in the blue-detuned MOT, and its lifetime is limited by collisions between the trapped atoms. We present measurements of the loss rate due to these ultracold collisions as a function of laser intensity and detuning. In the red-detuned MOTs, Sisyphus heating dominates at low speeds and Doppler cooling at higher speeds. Consequently, temperatures in the red-detuned MOTs are up to a thousand times higher than in the blue-detuned MOTs. One MOT forms large ring structures, with no density at the center, showing how atoms driven towards a non-zero equilibrium speed remain trapped by orbiting around the center. Another MOT demonstrates that magnetic mixing of the excited-state hyperfine levels can be an important mechanism in type-II MOTs.