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Title: Collisional relaxation of Feshbach molecules and three-body recombination in {sup 87}Rb Bose-Einstein condensates

Abstract

We predict the resonance-enhanced magnetic field dependence of atom-dimer relaxation and three-body recombination rates in a {sup 87}Rb Bose-Einstein condensate close to 1007 G. Our exact treatments of three-particle scattering explicitly include the dependence of the interactions on the atomic Zeeman levels. The Feshbach resonance distorts the entire diatomic energy spectrum, causing interferences in both loss phenomena. Our two independent experiments confirm the predicted recombination loss over a range of rate constants that spans four orders of magnitude.

Authors:
; ; ; ; ; ; ;  [1]; ; ; ;  [2]
  1. Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford, OX1 3PU (United Kingdom)
  2. Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, 85748 Garching (Germany)
Publication Date:
OSTI Identifier:
20982052
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. A; Journal Volume: 75; Journal Issue: 2; Other Information: DOI: 10.1103/PhysRevA.75.020702; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; ATOM-MOLECULE COLLISIONS; ATOMS; BOSE-EINSTEIN CONDENSATION; DIMERS; ENERGY SPECTRA; INTERACTIONS; INTERFERENCE; LOSSES; MAGNETIC FIELDS; MOLECULES; REACTION KINETICS; RECOMBINATION; RELAXATION; RESONANCE; RUBIDIUM 87; SCATTERING; THREE-BODY PROBLEM; ZEEMAN EFFECT

Citation Formats

Smirne, G., Godun, R. M., Cassettari, D., Boyer, V., Foot, C. J., Lee, M. D., Goral, K., Koehler, T., Volz, T., Syassen, N., Duerr, S., and Rempe, G.. Collisional relaxation of Feshbach molecules and three-body recombination in {sup 87}Rb Bose-Einstein condensates. United States: N. p., 2007. Web. doi:10.1103/PHYSREVA.75.020702.
Smirne, G., Godun, R. M., Cassettari, D., Boyer, V., Foot, C. J., Lee, M. D., Goral, K., Koehler, T., Volz, T., Syassen, N., Duerr, S., & Rempe, G.. Collisional relaxation of Feshbach molecules and three-body recombination in {sup 87}Rb Bose-Einstein condensates. United States. doi:10.1103/PHYSREVA.75.020702.
Smirne, G., Godun, R. M., Cassettari, D., Boyer, V., Foot, C. J., Lee, M. D., Goral, K., Koehler, T., Volz, T., Syassen, N., Duerr, S., and Rempe, G.. Thu . "Collisional relaxation of Feshbach molecules and three-body recombination in {sup 87}Rb Bose-Einstein condensates". United States. doi:10.1103/PHYSREVA.75.020702.
@article{osti_20982052,
title = {Collisional relaxation of Feshbach molecules and three-body recombination in {sup 87}Rb Bose-Einstein condensates},
author = {Smirne, G. and Godun, R. M. and Cassettari, D. and Boyer, V. and Foot, C. J. and Lee, M. D. and Goral, K. and Koehler, T. and Volz, T. and Syassen, N. and Duerr, S. and Rempe, G.},
abstractNote = {We predict the resonance-enhanced magnetic field dependence of atom-dimer relaxation and three-body recombination rates in a {sup 87}Rb Bose-Einstein condensate close to 1007 G. Our exact treatments of three-particle scattering explicitly include the dependence of the interactions on the atomic Zeeman levels. The Feshbach resonance distorts the entire diatomic energy spectrum, causing interferences in both loss phenomena. Our two independent experiments confirm the predicted recombination loss over a range of rate constants that spans four orders of magnitude.},
doi = {10.1103/PHYSREVA.75.020702},
journal = {Physical Review. A},
number = 2,
volume = 75,
place = {United States},
year = {Thu Feb 15 00:00:00 EST 2007},
month = {Thu Feb 15 00:00:00 EST 2007}
}
  • We present measurements of the loss-rate coefficients K{sub am} and K{sub mm} caused by inelastic atom-molecule and molecule-molecule collisions. A thermal cloud of atomic {sup 87}Rb is prepared in an optical dipole trap. A magnetic field is ramped across the Feshbach resonance at 1007.4 G. This associates atom pairs to molecules. A measurement of the molecule loss at 1005.8 G yields K{sub am}=2x10{sup -10} cm{sup 3}/s. Additionally, the atoms can be removed with blast light. In this case, the measured molecule loss yields K{sub mm}=3x10{sup -10} cm{sup 3}/s.
  • We experimentally studied the spin-dependent collision dynamics of {sup 87}Rb spin-2 Bose-Einstein condensates confined in an optical trap. The condensed atoms were initially populated in the |F=2,m{sub F}=0> state, and their time evolutions in the trap were measured in the presence of external magnetic field strengths ranging from 0.1 to 3.0 G. The atom loss rate due to inelastic two-body collisions was found to be 1.4(2)x10{sup -13} cm{sup 3} s{sup -1}. Spin mixing in the F=2 manifold developed dramatically for the first few tens of milliseconds, and the oscillations in the population distribution between different magnetic components were observed overmore » a limited range of magnetic field strengths. The antiferromagnetic property of this system was deduced from the magnetic field dependence on the evolution of relative populations for each m{sub F} component.« less
  • We present a compact experimental apparatus for Bose-Einstein condensation of {sup 87}Rb in the |F  =  2, m{sub F} = + 2〉 state. A pre-cooled atomic beam of {sup 87}Rb is obtained by using an unbalanced magneto-optical trap, allowing controlled transfer of trapped atoms from the first vacuum chamber to the science chamber. Here, atoms are transferred to a hybrid trap, as produced by overlapping a magnetic quadrupole trap with a far-detuned optical trap with crossed beam configuration, where forced radiofrequency evaporation is realized. The final evaporation leading to Bose-Einstein condensation is then performed by exponentially lowering the optical trapmore » depth. Control and stabilization systems of the optical trap beams are discussed in detail. The setup reliably produces a pure condensate in the |F = 2, m{sub F} = + 2〉 state in 50 s, which includes 33 s loading of the science magneto-optical trap and 17 s forced evaporation.« less
  • The loss of ultracold trapped atoms in the vicinity of a Feshbach resonance is treated as a two-stage reaction, using the Breit-Wigner theory. The first stage is the formation of a resonant diatomic molecule, and the second one is its deactivation by inelastic collisions with other atoms. This model is applied to the analysis of recent experiments on {sup 87}Rb, leading to an estimated value of 7x10{sup -11} cm{sup 3}/s for the deactivation rate coefficient.
  • We investigate phase separation of Bose-Einstein condensates (BECs) of two-component atoms and one-component molecules with a homonuclear Feshbach resonance. We develop a full model for dilute atomic and molecular gases including correlation of the Feshbach resonance and all kinds of interparticle interactions, and numerically calculate order parameters of the BECs in spherical harmonic oscillator traps at zero temperature with the Bogoliubov's classical field approximation. As a result, we find out that the Feshbach resonance can induce two types of phase separation. The actual phase structures and density profiles of the trapped gases are predicted in the whole parameter region, frommore » the atom-dominant regime to the molecule-dominant regime. We focus on the role of the molecules in the phase separation. Especially in the atom-dominant regime, the role of the molecules is described through effective interactions derived from our model. Furthermore we show that a perturbative and semiclassical limit of our model reproduces the conventional atomic BEC (single-channel) model.« less