Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:0805.3708 · Physical Review A

Light-assisted collisional loss in a Rb85∕87 ultracold optical trap

Anthony Gorges, N. S. Bingham, Michael K. DeAngelo, Mathew Hamilton, Jacob Roberts

Published Sep 18, 2008• 13 citations
arXivHTMLPDF

Abstract

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.

DOI
10.1103/physreva.78.033420

Related papers

Inter-isotope effects in optimal dual-isotope loading into a shallow optical trap

M S Hamilton, A R Gorges, J L Roberts

Examination of loading the isotopes $^{85}$Rb and $^{87}$Rb simultaneously into a shallow far-off-resonance trap (FORT) has revealed an unexpected decrease in maximum atom number loaded as compared to loading either isotope alone. The simultaneous loading of the FORT will be affected by additional homonuclear and heteronuclear light-assisted collisional losses. However, these losses are measured and found to be insufficient to explain the observed drop in total number of atoms loaded into the FORT. We find that our observations are consistent with a decrease in loading rate caused by inter-isotope disruptions of the efficient laser cooling required to load atoms into the optical trap.

arXiv:1202.2165•Journal of Physics B Atomic Molecular and Optical Physics•Apr 19, 2012•7 citations

Trap-loss collisions of 85 Rb and 87 Rb : Dependence on trap parameters

S. D. Gensemer, V. Sánchez-Villicaña, K. Y. N. Tan +2 more

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 A•Nov 1, 1997•57 citations

Comparison of trap-loss collision spectra for Rb85 and Rb87

Paul Feng, Dominikus Hoffmann, Thad G Walker

We present measurements of excited-state trap-loss collisions of optically trapped $^{85}\mathrm{Rb}$ and $^{87}\mathrm{Rb}$ atoms as a function of the frequency of the light used to excite the colliding atom pairs. For detunings outside the excited-state hyperfine structure, the trap-loss rates are found to be the same for the two isotopes. For detunings inside the excited-state hyperfine structure, $^{87}\mathrm{Rb}$ collisions occur at a substantially lower rate than those of $^{85}\mathrm{Rb}$. The spectra make it clear that the long-range dynamics of the collisions are strongly modified by the excited-state hyperfine structure, and that the dynamics are different for the two isotopes.

Physical Review A•May 1, 1993•29 citations

Effects of laser light on ultracold atom collisions

V. Sánchez-Villicaña

Measurements of the temperature dependence of trap loss collisions of laser-cooled rubidium atoms are presented. A significant suppression of the rate of collisions between ground- and excited-state atoms is observed for temperatures below $\\sim$70 $\\mu$K. In such inelastic collisions, the atomic excitation takes place at long range and must survive against spontaneous decay to short range. Our results are consistent with recent predictions for the low temperature suppression of these collisions due to reduced survival of atomic excitation at low collision velocities.^ We report on measurements of trap loss collisions between ultracold Rb atoms which are confined in a magneto-optical trap. Both isotopes $\\sp{85}$Rb and $\\sp{87}$Rb have been studied over wide range of trap laser intensities and detunings. The trap loss collision rates exhibit variations over 3 orders of magnitude. We observe significant differences between the isotopes. At large detunings the ability of the trap to recapture products of the hyperfine-changing collisions 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.^ Using laser light tuned to a repulsive molecular potential, we have been able to suppress inelastic ground-state hyperfine changing collisions between ultracold $\\sp{87}$Rb atoms. Adiabatic excitation to the repulsive curve alters the atomic trajectories and prevents the atoms from approaching close enough for the hyperfine change to occur. Experimental results show suppressions up to $\\sim$50% and are in reasonable agreement with a simple Landau-Zener model.^ Finally, we have observed a significant cooperative effect in ultracold trap loss collisions induced by two separate lasers. One laser, tuned close to the atomic resonance, excites the atom pair to an attractive potential at long range. The resulting acceleration and deflection give rise to an enhancement in the collisional flux of ground-state atoms reaching short range, as probed by a second laser. Enhancements up to a factor of $\\sim$3 have been observed. ^

•Jan 1, 1996•0 citations

Magneto-optical trapping and ultracold collisions of potassium atoms

R. S. Williamson, Thad G Walker

We present measurements of loading and loss rates for a vapor-cell optical trap of the two naturally occurring potassium isotopes 39K and 41K. The unresolved excited-state hyperfine structure makes trapping of K fundamentally different from trapping of the other alkalis and leads to an enhanced loading rate. We measure the loading rate as a function of laser intensity, beam size, and detuning and find that the results are in reasonable agreement with a simple rate-equation model for the loading process. The dependence of the loss rate on trapped-atom density determines the contribution to the loss rates from excited-state collisions. We find a substantial difference between the collisional loss rates for the two isotopes.

Journal of the Optical Society of America B•Aug 1, 1995•47 citations

Measurements of Rb trap-loss collision spectra

D. Hofffmann, P. Feng, Thad G Walker

We describe studies of excited-state/ground-state collisions between optically trapped Rb atoms. Collision rates are deduced from the transients observed as atoms are loaded into a vapor-cell optical trap. The rates are measured as a function of the frequency of the light used to excite the atom pairs. A comparison of the results for 85Rb and 87Rb shows that excited-state hyperfine interactions play a vital role in the dynamics of the collisions. In addition, the absolute rates are smaller than those expected from recent models.

Journal of the Optical Society of America B•May 1, 1994•44 citations
We have studied heteronuclear and homonuclear excited-state--ground-state collisions by loading both 85Rb^{85}\mathrm{Rb}85Rb and 87Rb^{87}\mathrm{Rb}87Rb 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 (15mW∕cm2)(15\phantom{\rule{0.3em}{0ex}}\mathrm{mW}∕{\mathrm{cm}}^{2})(15mW∕cm2). These losses are important limitations in loading dual isotope optical traps.
Examination of loading the isotopes 85^{85}85Rb and 87^{87}87Rb simultaneously into a shallow far-off-resonance trap (FORT) has revealed an unexpected decrease in maximum atom number loaded as compared to loading either isotope alone. The simultaneous loading of the FORT will be affected by additional homonuclear and heteronuclear light-assisted collisional losses. However, these losses are measured and found to be insufficient to explain the observed drop in total number of atoms loaded into the FORT. We find that our observations are consistent with a decrease in loading rate caused by inter-isotope disruptions of the efficient laser cooling required to load atoms into the optical trap.
We report on measurements of trap-loss collisions between ultracold Rb atoms that are confined in a magneto-optical trap. Both isotopes, 85Rb{}^{85}\mathrm{Rb}85Rb and 87Rb,{}^{87}\mathrm{Rb},87Rb, 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 present measurements of excited-state trap-loss collisions of optically trapped 85Rb^{85}\mathrm{Rb}85Rb and 87Rb^{87}\mathrm{Rb}87Rb atoms as a function of the frequency of the light used to excite the colliding atom pairs. For detunings outside the excited-state hyperfine structure, the trap-loss rates are found to be the same for the two isotopes. For detunings inside the excited-state hyperfine structure, 87Rb^{87}\mathrm{Rb}87Rb collisions occur at a substantially lower rate than those of 85Rb^{85}\mathrm{Rb}85Rb. The spectra make it clear that the long-range dynamics of the collisions are strongly modified by the excited-state hyperfine structure, and that the dynamics are different for the two isotopes.
Measurements of the temperature dependence of trap loss collisions of laser-cooled rubidium atoms are presented. A significant suppression of the rate of collisions between ground- and excited-state atoms is observed for temperatures below $\\sim$70 mu\\mumuK. In such inelastic collisions, the atomic excitation takes place at long range and must survive against spontaneous decay to short range. Our results are consistent with recent predictions for the low temperature suppression of these collisions due to reduced survival of atomic excitation at low collision velocities.^ We report on measurements of trap loss collisions between ultracold Rb atoms which are confined in a magneto-optical trap. Both isotopes sp85\\sp{85}sp85Rb and sp87\\sp{87}sp87Rb have been studied over wide range of trap laser intensities and detunings. The trap loss collision rates exhibit variations over 3 orders of magnitude. We observe significant differences between the isotopes. At large detunings the ability of the trap to recapture products of the hyperfine-changing collisions 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.^ Using laser light tuned to a repulsive molecular potential, we have been able to suppress inelastic ground-state hyperfine changing collisions between ultracold sp87\\sp{87}sp87Rb atoms. Adiabatic excitation to the repulsive curve alters the atomic trajectories and prevents the atoms from approaching close enough for the hyperfine change to occur. Experimental results show suppressions up to $\\sim$50% and are in reasonable agreement with a simple Landau-Zener model.^ Finally, we have observed a significant cooperative effect in ultracold trap loss collisions induced by two separate lasers. One laser, tuned close to the atomic resonance, excites the atom pair to an attractive potential at long range. The resulting acceleration and deflection give rise to an enhancement in the collisional flux of ground-state atoms reaching short range, as probed by a second laser. Enhancements up to a factor of $\\sim$3 have been observed. ^
We present measurements of loading and loss rates for a vapor-cell optical trap of the two naturally occurring potassium isotopes 39K and 41K. The unresolved excited-state hyperfine structure makes trapping of K fundamentally different from trapping of the other alkalis and leads to an enhanced loading rate. We measure the loading rate as a function of laser intensity, beam size, and detuning and find that the results are in reasonable agreement with a simple rate-equation model for the loading process. The dependence of the loss rate on trapped-atom density determines the contribution to the loss rates from excited-state collisions. We find a substantial difference between the collisional loss rates for the two isotopes.
We describe studies of excited-state/ground-state collisions between optically trapped Rb atoms. Collision rates are deduced from the transients observed as atoms are loaded into a vapor-cell optical trap. The rates are measured as a function of the frequency of the light used to excite the atom pairs. A comparison of the results for 85Rb and 87Rb shows that excited-state hyperfine interactions play a vital role in the dynamics of the collisions. In addition, the absolute rates are smaller than those expected from recent models.