01059nas a2200145 4500008004100000245006200041210006100103260001400164490000700178520062000185100002200805700001900827700002300846856004400869 2005 eng d00aSpontaneous dissociation of long-range Feshbach molecules0 aSpontaneous dissociation of longrange Feshbach molecules c2005/1/180 v943 a We study the spontaneous dissociation of diatomic molecules produced in cold
atomic gases via magnetically tunable Feshbach resonances. We provide a
universal formula for the lifetime of these molecules that relates their decay
to the scattering length and the loss rate constant for inelastic spin
relaxation. Our universal treatment as well as our exact coupled channels
calculations for $^{85}$Rb dimers predict a suppression of the decay over
several orders of magnitude when the scattering length is increased. Our
predictions are in good agreement with recent measurements of the lifetime of
$^{85}$Rb$_2$.
1 aKoehler, Thorsten1 aTiesinga, Eite1 aJulienne, Paul, S. uhttp://arxiv.org/abs/cond-mat/0408387v202281nas a2200181 4500008004100000245009200041210006900133260001500202300001600217490000700233520170600240100002101946700002201967700002401989700001902013700002302032856004402055 2004 eng d00aAdiabatic association of ultracold molecules via magnetic field tunable interactions
0 aAdiabatic association of ultracold molecules via magnetic field c2004/09/14 a3457 - 35000 v373 a We consider in detail the situation of applying a time dependent external
magnetic field to a 87Rb atomic Bose-Einstein condensate held in a harmonic
trap, in order to adiabatically sweep the interatomic interactions across a
Feshbach resonance to produce diatomic molecules. To this end, we introduce a
minimal two-body Hamiltonian depending on just five measurable parameters of a
Feshbach resonance, which accurately determines all low energy binary
scattering observables, in particular, the molecular conversion efficiency of
just two atoms. Based on this description of the microscopic collision
phenomena, we use the many-body theory of T. Koehler and K. Burnett [Phys. Rev.
A 65, 033601 (2002)] to study the efficiency of the association of molecules in
a 87Rb Bose-Einstein condensate during a linear passage of the magnetic field
strength across the 100 mT Feshbach resonance. We explore different,
experimentally accessible, parameter regimes, and compare the predictions of
Landau-Zener, configuration interaction, and two level mean field calculations
with those of the microscopic many-body approach. Our comparative studies
reveal a remarkable insensitivity of the molecular conversion efficiency with
respect to both the details of the microscopic binary collision physics and the
coherent nature of the Bose-Einstein condensed gas, provided that the magnetic
field strength is varied linearly. We provide the reasons for this universality
of the molecular production achieved by linear ramps of the magnetic field
strength, and identify the Landau-Zener coefficient determined by F.H. Mies et
al. [Phys. Rev. A 61, 022721 (2000)] as the main parameter that controls the
efficiency.
1 aGoral, Krzysztof1 aKoehler, Thorsten1 aGardiner, Simon, A.1 aTiesinga, Eite1 aJulienne, Paul, S. uhttp://arxiv.org/abs/cond-mat/0312178v5