Physical Review A

Ultracold 87Rb ground-state hyperfine-changing collisions in the presence and absence of laser light

S. D. Gensemer, P. L. Gould, Paul J. Leo, Eite Tiesinga, Carl J. Williams

Published Aug 18, 2000• 11 citations

Abstract

We have measured the rate of hyperfine-changing collisions between ground-state ${}^{87}\mathrm{Rb}$ atoms in a magneto-optical trap. Using a population switching technique, we directly measure the rate of these collisions in both the presence and absence of near-resonant trap laser light. We see a dramatic enhancement of the collision rate by the light and observe that, in the absence of the light, the rate increases with increasing temperature. There is consistency between this latter measured rate at temperatures below $\ensuremath{\sim}100$ $\ensuremath{\mu}\mathrm{K}$ and theoretical calculations constrained by other recent experiments.

DOI: 10.1103/physreva.62.030702

Related papers

Effects of laser light on ultracold atom collisions

V. Sánchez-Villicaña

Jan 1, 19960 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

Physical Review ANov 1, 199757 citations

Collisions in a dual-species magneto-optical trap of molecules and atoms

Sarunas Jurgilas, A. Chakraborty, C. J. H. Rich +4 more

arXiv:2104.09990New Journal of PhysicsJun 18, 20219 citations

Hyperfine-changing collisions in an optically trapped gas of ultracold cesium and lithium

Marcel Carto Constantin Mudrich, Stephan Kraft, Jörg Lange +3 more

Physical Review ADec 17, 200423 citations

Investigation of cold collision in a Rb–Cs magneto-optical trap

Zhonghua Ji, Jizhou Wu, Hongshan Zhang +6 more

We have measured the interspecies trap loss rate coefficient βRb-Cs between ultracold Rb and Cs atoms as a function of Rb trapping laser intensity. The trap loss rate coefficient decreases as the Rb trapping laser intensity increases where the trap loss caused by hyperfine-state changing collision is suppressed due to the increasing Rb trap depth. The experimental results agree with the calculated critical intensity IC of Rb trapping laser by a simple Doppler model.

Journal of Physics B Atomic Molecular and Optical PhysicsJan 12, 20115 citations

Measurements of Rb trap-loss collision spectra

D. Hofffmann, P. Feng, Thad G Walker

Journal of the Optical Society of America BMay 1, 199444 citations

Physical Review A

Ultracold 87Rb ground-state hyperfine-changing collisions in the presence and absence of laser light

S. D. Gensemer, P. L. Gould, Paul J. Leo, Eite Tiesinga, Carl J. Williams

Published Aug 18, 2000• 11 citations

Publisher

Abstract

We have measured the rate of hyperfine-changing collisions between ground-state

{}^{87}\mathrm{Rb}

atoms in a magneto-optical trap. Using a population switching technique, we directly measure the rate of these collisions in both the presence and absence of near-resonant trap laser light. We see a dramatic enhancement of the collision rate by the light and observe that, in the absence of the light, the rate increases with increasing temperature. There is consistency between this latter measured rate at temperatures below

\ensuremath{\sim}100

\ensuremath{\mu}\mathrm{K}

and theoretical calculations constrained by other recent experiments.

DOI: 10.1103/physreva.62.030702

Related papers

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. ^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, 19960 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.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

Collisions in a dual-species magneto-optical trap of molecules and atoms

Sarunas Jurgilas, A. Chakraborty, C. J. H. Rich +4 more

Abstract We study inelastic collisions between CaF molecules and 87Rb atoms in a dual-species magneto-optical trap. The presence of atoms increases the loss rate of molecules from the trap. By measuring the loss rates and density distributions, we determine a collisional loss rate coefficient k 2 = (1.43 ± 0.29) × 10−10 cm3 s−1 at a temperature of 2.4 mK. We show that this is not substantially changed by light-induced collisions or by varying the populations of excited-state atoms and molecules. The observed loss rate is close to the universal rate expected in the presence of fast loss at short range, and can be explained by rotation-changing collisions in the ground electronic state.Abstract We study inelastic collisions between CaF molecules and 87Rb atoms in a dual-species magneto-optical trap. The presence of atoms increases the loss rate of molecules from the trap. By measuring the loss rates and density distributions, we determine a collisional loss rate coefficient k 2 = (1.43 ± 0.29) × 10−10 cm3 s−1 at a temperature of 2.4 mK. We show that this is not substantially changed by light-induced collisions or by varying the populations of excited-state atoms and molecules. The observed loss rate is close to the universal rate expected in the presence of fast loss at short range, and can be explained by rotation-changing collisions in the ground electronic state.

arXiv:2104.09990New Journal of PhysicsJun 18, 20219 citations

Hyperfine-changing collisions in an optically trapped gas of ultracold cesium and lithium

Marcel Carto Constantin Mudrich, Stephan Kraft, Jörg Lange +3 more

We present measurements of the rate of hyperfine-state-changing collisions of unpolarized cesium $(^{133}\mathrm{Cs})$ and lithium $(^{7}\mathrm{Li})$ atoms confined in an optical dipole trap in the temperature range between 30 and $130\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{K}$. To infer rate coefficients from trap-loss data, we derive a simple thermodynamic model describing relaxation heating as a consequence of atom loss in a conservative potential. For hyperfine-changing $\mathrm{Cs}\text{\ensuremath{-}}\mathrm{Cs}$ collisions, the experimental results are compared with theoretical predictions and excellent agreement is found. Hyperfine-state-changing collisions in a mixture of lithium and cesium atoms are observed and rate coefficients are inferred for all combinations of hyperfine ground-state asymptotes.We present measurements of the rate of hyperfine-state-changing collisions of unpolarized cesium $(^{133}\mathrm{Cs})$ and lithium $(^{7}\mathrm{Li})$ atoms confined in an optical dipole trap in the temperature range between 30 and $130\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{K}$. To infer rate coefficients from trap-loss data, we derive a simple thermodynamic model describing relaxation heating as a consequence of atom loss in a conservative potential. For hyperfine-changing $\mathrm{Cs}\text{\ensuremath{-}}\mathrm{Cs}$ collisions, the experimental results are compared with theoretical predictions and excellent agreement is found. Hyperfine-state-changing collisions in a mixture of lithium and cesium atoms are observed and rate coefficients are inferred for all combinations of hyperfine ground-state asymptotes.

Physical Review ADec 17, 200423 citations

Investigation of cold collision in a Rb–Cs magneto-optical trap

Zhonghua Ji, Jizhou Wu, Hongshan Zhang +6 more

Journal of Physics B Atomic Molecular and Optical PhysicsJan 12, 20115 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.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 BMay 1, 199444 citations

We have measured the rate of hyperfine-changing collisions between ground-state

{}^{87}\mathrm{Rb}

\ensuremath{\sim}100

\ensuremath{\mu}\mathrm{K}

and theoretical calculations constrained by other recent experiments.

\\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. ^

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 present measurements of the rate of hyperfine-state-changing collisions of unpolarized cesium

(^{133}\mathrm{Cs})

and lithium

(^{7}\mathrm{Li})

atoms confined in an optical dipole trap in the temperature range between 30 and $130\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{K}$. To infer rate coefficients from trap-loss data, we derive a simple thermodynamic model describing relaxation heating as a consequence of atom loss in a conservative potential. For hyperfine-changing $\mathrm{Cs}\text{\ensuremath{-}}\mathrm{Cs}$ collisions, the experimental results are compared with theoretical predictions and excellent agreement is found. Hyperfine-state-changing collisions in a mixture of lithium and cesium atoms are observed and rate coefficients are inferred for all combinations of hyperfine ground-state asymptotes.