01486nas a2200181 4500008004100000245004800041210004800089260001500137300001100152490000700163520100000170100001801170700002101188700002301209700001901232700001701251856003601268 2016 eng d00aPhotoassociation of spin polarized Chromium0 aPhotoassociation of spin polarized Chromium c2016/02/29 a0214060 v933 aWe report the homonuclear photoassociation (PA) of ultracold 52Cr atoms in an optical dipole trap. This constitutes the first measurement of PA in an element with total electron spin S~>1. Although Cr, with its 7S3 ground and 7P4,3,2 excited states, is expected to have a complicated PA spectrum we show that a spin polarized cloud exhibits a remarkably simple PA spectrum when circularly polarized light is applied. Over a scan range of 20 GHz below the 7P3 asymptote we observe two distinct vibrational series each following a LeRoy-Bernstein law for a C3/R3 potential with excellent agreement. We determine the C3 coefficients of the Hund's case c) relativistic adiabatic potentials to be -1.83±0.02 a.u. and -1.46±0.01a.u.. Theoretical non-rotating Movre-Pichler calculations enable a first assignment of the series to Ω=6u and 5g potential energy curves. In a different set of experiments we disturb the selection rules by a transverse magnetic field which leads to additional PA series.1 aRührig, Jahn1 aBäuerle, Tobias1 aJulienne, Paul, S.1 aTiesinga, Eite1 aPfau, Tilman uhttp://arxiv.org/abs/1512.0437801195nas a2200157 4500008004100000245006200041210006200103260001300165490000700178520072500185100002200910700001900932700002600951700002300977856003701000 2012 eng d00aResonant control of polar molecules in an optical lattice0 aResonant control of polar molecules in an optical lattice c2012/2/80 v853 a We study the resonant control of two nonreactive polar molecules in an
optical lattice site, focussing on the example of RbCs. Collisional control can
be achieved by tuning bound states of the intermolecular dipolar potential, by
varying the applied electric field or trap frequency. We consider a wide range
of electric fields and trapping geometries, showing that a three-dimensional
optical lattice allows for significantly wider avoided crossings than free
space or quasi-two dimensional geometries. Furthermore, we find that dipolar
confinement induced resonances can be created with reasonable trapping
frequencies and electric fields, and have widths that will enable useful
control in forthcoming experiments.
1 aHanna, Thomas, M.1 aTiesinga, Eite1 aMitchell, William, F.1 aJulienne, Paul, S. uhttp://arxiv.org/abs/1111.0227v101279nas a2200181 4500008004100000245009100041210006900132260001400201490000700215520071200222100002000934700002000954700001900974700002500993700002301018700001901041856003701060 2011 eng d00aSpatial separation in a thermal mixture of ultracold $^{174}$Yb and $^{87}$Rb atoms
0 aSpatial separation in a thermal mixture of ultracold 174 Yb and c2011/4/210 v833 a We report on the observation of unusually strong interactions in a thermal
mixture of ultracold atoms which cause a significant modification of the
spatial distribution. A mixture of $^{87}$Rb and $^{174}$Yb with a temperature
of a few $\mu$K is prepared in a hybrid trap consisting of a bichromatic
optical potential superimposed on a magnetic trap. For suitable trap parameters
and temperatures, a spatial separation of the two species is observed. We infer
that the separation is driven by a large interaction strength between
$^{174}$Yb and $^{87}$Rb accompanied by a large three-body recombination rate.
Based on this assumption we have developed a diffusion model which reproduces
our observations.
1 aBaumer, Florian1 aMünchow, Frank1 aGörlitz, Axel1 aMaxwell, Stephen, E.1 aJulienne, Paul, S.1 aTiesinga, Eite uhttp://arxiv.org/abs/1104.1722v101723nas a2200157 4500008004100000245008700041210006900128260001500197300001100212490000700223520123400230100002201464700001901486700002301505856003701528 2010 eng d00aCreation and manipulation of Feshbach resonances with radio-frequency radiation
0 aCreation and manipulation of Feshbach resonances with radiofrequ c2010/08/12 a0830310 v123 a We present a simple technique for studying collisions of ultracold atoms in
the presence of a magnetic field and radio-frequency radiation (rf). Resonant
control of scattering properties can be achieved by using rf to couple a
colliding pair of atoms to a bound state. We show, using the example of 6Li,
that in some ranges of rf frequency and magnetic field this can be done without
giving rise to losses. We also show that halo molecules of large spatial extent
require much less rf power than deeply bound states. Another way to exert
resonant control is with a set of rf-coupled bound states, linked to the
colliding pair through the molecular interactions that give rise to
magnetically tunable Feshbach resonances. This was recently demonstrated for
87Rb [Kaufman et al., Phys. Rev. A 80:050701(R), 2009]. We examine the
underlying atomic and molecular physics which made this possible. Lastly, we
consider the control that may be exerted over atomic collisions by placing
atoms in superpositions of Zeeman states, and suggest that it could be useful
where small changes in scattering length are required. We suggest other species
for which rf and magnetic field control could together provide a useful tuning
mechanism.
1 aHanna, Thomas, M.1 aTiesinga, Eite1 aJulienne, Paul, S. uhttp://arxiv.org/abs/1004.0636v101137nas a2200157 4500008004100000245008200041210006900123260001300192490000700205520065000212100001500862700001900877700002300896700002300919856003700942 2009 eng d00aCollisional cooling of ultra-cold atom ensembles using Feshbach resonances
0 aCollisional cooling of ultracold atom ensembles using Feshbach r c2009/9/80 v803 a We propose a new type of cooling mechanism for ultra-cold fermionic atom
ensembles, which capitalizes on the energy dependence of inelastic collisions
in the presence of a Feshbach resonance. We first discuss the case of a single
magnetic resonance, and find that the final temperature and the cooling rate is
limited by the width of the resonance. A concrete example, based on a p-wave
resonance of $^{40}$K, is given. We then improve upon this setup by using both
a very sharp optical or radio-frequency induced resonance and a very broad
magnetic resonance and show that one can improve upon temperatures reached with
current technologies.
1 aMathey, L.1 aTiesinga, Eite1 aJulienne, Paul, S.1 aClark, Charles, W. uhttp://arxiv.org/abs/0903.2568v101547nas a2200157 4500008004100000245009000041210006900131260001500200300001100215490000700226520105100233100002601284700001901310700002301329856003701352 2009 eng d00aMulti-channel modelling of the formation of vibrationally cold polar KRb molecules
0 aMultichannel modelling of the formation of vibrationally cold po c2009/05/14 a0550430 v113 a We describe the theoretical advances that influenced the experimental
creation of vibrationally and translationally cold polar $^{40}$K$^{87}$Rb
molecules \cite{nphys08,science08}. Cold molecules were created from
very-weakly bound molecules formed by magnetic field sweeps near a Feshbach
resonance in collisions of ultra-cold $^{40}$K and $^{87}$Rb atoms. Our
analysis include the multi-channel bound-state calculations of the hyperfine
and Zeeman mixed X$^1\Sigma^+$ and a$^3\Sigma^+$ vibrational levels. We find
excellent agreement with the hyperfine structure observed in experimental data.
In addition, we studied the spin-orbit mixing in the intermediate state of the
Raman transition. This allowed us to investigate its effect on the
vibrationally-averaged transition dipole moment to the lowest ro-vibrational
level of the X$^1\Sigma^+$ state. Finally, we obtained an estimate of the
polarizability of the initial and final ro-vibrational states of the Raman
transition near frequencies relevant for optical trapping of the molecules.
1 aKotochigova, Svetlana1 aTiesinga, Eite1 aJulienne, Paul, S. uhttp://arxiv.org/abs/0901.1486v101221nas a2200145 4500008004100000245006600041210006600107260001400173490000700187520078000194100002200974700001900996700002301015856003701038 2009 eng d00aPrediction of Feshbach resonances from three input parameters0 aPrediction of Feshbach resonances from three input parameters c2009/4/300 v793 a We have developed a model of Feshbach resonances in gases of ultracold alkali
metal atoms using the ideas of multichannel quantum defect theory. Our model
requires just three parameters describing the interactions - the singlet and
triplet scattering lengths, and the long range van der Waals coefficient - in
addition to known atomic properties. Without using any further details of the
interactions, our approach can accurately predict the locations of resonances.
It can also be used to find the singlet and triplet scattering lengths from
measured resonance data. We apply our technique to $^{6}$Li--$^{40}$K and
$^{40}$K--$^{87}$Rb scattering, obtaining good agreement with experimental
results, and with the more computationally intensive coupled channels
technique.
1 aHanna, Thomas, M.1 aTiesinga, Eite1 aJulienne, Paul, S. uhttp://arxiv.org/abs/0903.0884v201381nas a2200145 4500008004100000245007000041210006900111260001400180490000700194520093200201100002301133700001901156700002301175856003701198 2008 eng d00aAvoided crossings between bound states of ultracold Cesium dimers0 aAvoided crossings between bound states of ultracold Cesium dimer c2008/11/50 v783 a We present an efficient new computational method for calculating the binding
energies of the bound states of ultracold alkali-metal dimers in the presence
of magnetic fields. The method is based on propagation of coupled differential
equations and does not use a basis set for the interatomic distance coordinate.
It is much more efficient than the previous method based on a radial basis set
and allows many more spin channels to be included. This is particularly
important in the vicinity of avoided crossings between bound states. We
characterize a number of different avoided crossings in Cs_2 and compare our
converged calculations with experimental results. Small but significant
discrepancies are observed in both crossing strengths and level positions,
especially for levels with l symmetry (rotational angular momentum L=8). The
discrepancies should allow the development of improved potential models in the
future.
1 aHutson, Jeremy, M.1 aTiesinga, Eite1 aJulienne, Paul, S. uhttp://arxiv.org/abs/0806.2583v101063nas a2200145 4500008004100000245005700041210005500098260001300153490000800166520064500174100001900819700001900838700002300857856003700880 2008 eng d00aTwo-body transients in coupled atomic-molecular BECs0 aTwobody transients in coupled atomicmolecular BECs c2008/3/30 v1003 a We discuss the dynamics of an atomic Bose-Einstein condensate when pairs of
atoms are converted into molecules by single-color photoassociation. Three main
regimes are found and it is shown that they can be understood on the basis of
time-dependent two-body theory. In particular, the so-called rogue dissociation
regime [Phys. Rev. Lett., 88, 090403 (2002)], which has a density-dependent
limit on the photoassociation rate, is identified with a transient regime of
the two-atom dynamics exhibiting universal properties. Finally, we illustrate
how these regimes could be explored by photoassociating condensates of
alkaline-earth atoms.
1 aNaidon, Pascal1 aTiesinga, Eite1 aJulienne, Paul, S. uhttp://arxiv.org/abs/0707.2963v201051nas a2200133 4500008004100000245010600041210006900147260001500216520058800231100001900819700001900838700002300857856003700880 2007 eng d00aCoherent, adiabatic and dissociation regimes in coupled atomic-molecular Bose-Einstein condensates
0 aCoherent adiabatic and dissociation regimes in coupled atomicmol c2007/11/023 a We discuss the dynamics of a Bose-Einstein condensate of atoms which is
suddenly coupled to a condensate of molecules by an optical or magnetic
Feshbach resonance. Three limiting regimes are found and can be understood from
the transient dynamics occuring for each pair of atoms. This transient dynamics
can be summarised into a time-dependent shift and broadening of the molecular
state. A simple Gross-Pitaevskii picture including this shift and broadening is
proposed to describe the system in the three regimes. Finally, we suggest how
to explore these regimes experimentally.
1 aNaidon, Pascal1 aTiesinga, Eite1 aJulienne, Paul, S. uhttp://arxiv.org/abs/0711.0397v201036nas a2200169 4500008004100000245009800041210006900139260001500208300001200223490000600235520049500241100001900736700001900755700002600774700002300800856004300823 2007 eng d00aEffective-range description of a Bose gas under strong one- or two-dimensional confinement
0 aEffectiverange description of a Bose gas under strong one or two c2007/01/29 a19 - 190 v93 a We point out that theories describing s-wave collisions of bosonic atoms
confined in one- or two-dimensional geometries can be extended to much tighter
confinements than previously thought. This is achieved by replacing the
scattering length by an energy-dependent scattering length which was already
introduced for the calculation of energy levels under 3D confinement. This
replacement accurately predicts the position of confinement-induced resonances
in strongly confined geometries.
1 aNaidon, Pascal1 aTiesinga, Eite1 aMitchell, William, F.1 aJulienne, Paul, S. uhttp://arxiv.org/abs/physics/0607140v201042nas a2200157 4500008004100000245006600041210006500107260001500172490000700187520057000194100001200764700001900776700002300795700002300818856004300841 2005 eng d00aMultichannel quantum-defect theory for slow atomic collisions0 aMultichannel quantumdefect theory for slow atomic collisions c2005/10/280 v723 a We present a multichannel quantum-defect theory for slow atomic collisions
that takes advantages of the analytic solutions for the long-range potential,
and both the energy and the angular-momentum insensitivities of the short-range
parameters. The theory provides an accurate and complete account of scattering
processes, including shape and Feshbach resonances, in terms of a few
parameters such as the singlet and the triplet scattering lengths. As an
example, results for $^{23}$Na-$^{23}$Na scattering are presented and compared
close-coupling calculations.
1 aGao, Bo1 aTiesinga, Eite1 aWilliams, Carl, J.1 aJulienne, Paul, S. uhttp://arxiv.org/abs/physics/0508060v101059nas 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/0312178v501322nas a2200169 4500008004100000245007000041210006900111260001400180490000700194520079400201100002300995700002301018700002601041700001901067700002301086856004301109 2003 eng d00aUltracold collision properties of metastable alkaline-earth atoms0 aUltracold collision properties of metastable alkalineearth atoms c2003/2/130 v903 a Ultra-cold collisions of spin-polarized 24Mg,40Ca, and 88Sr in the metastable
3P2 excited state are investigated. We calculate the long-range interaction
potentials and estimate the scattering length and the collisional loss rate as
a function of magnetic field. The estimates are based on molecular potentials
between 3P2 alkaline-earth atoms obtained from ab initio atomic and molecular
structure calculations. The scattering lengths show resonance behavior due to
the appearance of a molecular bound state in a purely long-range interaction
potential and are positive for magnetic fields below 50 mT. A loss-rate model
shows that losses should be smallest near zero magnetic field and for fields
slightly larger than the resonance field, where the scattering length is also
positive.
1 aDerevianko, Andrei1 aPorsev, Sergey, G.1 aKotochigova, Svetlana1 aTiesinga, Eite1 aJulienne, Paul, S. uhttp://arxiv.org/abs/physics/0210076v1