%0 Journal Article
%J Physical Review A
%D 2016
%T Photoassociation of spin polarized Chromium
%A Jahn Rührig
%A Tobias Bäuerle
%A Paul S. Julienne
%A Eite Tiesinga
%A Tilman Pfau
%X We 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.
%B Physical Review A
%V 93
%P 021406
%8 2016/02/29
%G eng
%U http://arxiv.org/abs/1512.04378
%N 2
%R 10.1103/PhysRevA.93.021406
%0 Journal Article
%J Physical Review A
%D 2012
%T Resonant control of polar molecules in an optical lattice
%A Thomas M. Hanna
%A Eite Tiesinga
%A William F. Mitchell
%A Paul S. Julienne
%X 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.
%B Physical Review A
%V 85
%8 2012/2/8
%G eng
%U http://arxiv.org/abs/1111.0227v1
%N 2
%! Phys. Rev. A
%R 10.1103/PhysRevA.85.022703
%0 Journal Article
%J Physical Review A
%D 2011
%T Spatial separation in a thermal mixture of ultracold $^174$Yb and $^87$Rb atoms
%A Florian Baumer
%A Frank Münchow
%A Axel Görlitz
%A Stephen E. Maxwell
%A Paul S. Julienne
%A Eite Tiesinga
%X 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.
%B Physical Review A
%V 83
%8 2011/4/21
%G eng
%U http://arxiv.org/abs/1104.1722v1
%N 4
%! Phys. Rev. A
%R 10.1103/PhysRevA.83.040702
%0 Journal Article
%J New Journal of Physics
%D 2010
%T Creation and manipulation of Feshbach resonances with radio-frequency radiation
%A Thomas M. Hanna
%A Eite Tiesinga
%A Paul S. Julienne
%X 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.
%B New Journal of Physics
%V 12
%P 083031
%8 2010/08/12
%G eng
%U http://arxiv.org/abs/1004.0636v1
%N 8
%! New J. Phys.
%R 10.1088/1367-2630/12/8/083031
%0 Journal Article
%J Physical Review A
%D 2009
%T Collisional cooling of ultra-cold atom ensembles using Feshbach resonances
%A L. Mathey
%A Eite Tiesinga
%A Paul S. Julienne
%A Charles W. Clark
%X 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.
%B Physical Review A
%V 80
%8 2009/9/8
%G eng
%U http://arxiv.org/abs/0903.2568v1
%N 3
%! Phys. Rev. A
%R 10.1103/PhysRevA.80.030702
%0 Journal Article
%J New Journal of Physics
%D 2009
%T Multi-channel modelling of the formation of vibrationally cold polar KRb molecules
%A Svetlana Kotochigova
%A Eite Tiesinga
%A Paul S. Julienne
%X 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.
%B New Journal of Physics
%V 11
%P 055043
%8 2009/05/14
%G eng
%U http://arxiv.org/abs/0901.1486v1
%N 5
%! New J. Phys.
%R 10.1088/1367-2630/11/5/055043
%0 Journal Article
%J Physical Review A
%D 2009
%T Prediction of Feshbach resonances from three input parameters
%A Thomas M. Hanna
%A Eite Tiesinga
%A Paul S. Julienne
%X 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.
%B Physical Review A
%V 79
%8 2009/4/30
%G eng
%U http://arxiv.org/abs/0903.0884v2
%N 4
%! Phys. Rev. A
%R 10.1103/PhysRevA.79.040701
%0 Journal Article
%J Physical Review A
%D 2008
%T Avoided crossings between bound states of ultracold Cesium dimers
%A Jeremy M. Hutson
%A Eite Tiesinga
%A Paul S. Julienne
%X 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.
%B Physical Review A
%V 78
%8 2008/11/5
%G eng
%U http://arxiv.org/abs/0806.2583v1
%N 5
%! Phys. Rev. A
%R 10.1103/PhysRevA.78.052703
%0 Journal Article
%J Physical Review Letters
%D 2008
%T Two-body transients in coupled atomic-molecular BECs
%A Pascal Naidon
%A Eite Tiesinga
%A Paul S. Julienne
%X 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.
%B Physical Review Letters
%V 100
%8 2008/3/3
%G eng
%U http://arxiv.org/abs/0707.2963v2
%N 9
%! Phys. Rev. Lett.
%R 10.1103/PhysRevLett.100.093001
%0 Journal Article
%D 2007
%T Coherent, adiabatic and dissociation regimes in coupled atomic-molecular Bose-Einstein condensates
%A Pascal Naidon
%A Eite Tiesinga
%A Paul S. Julienne
%X 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.
%8 2007/11/02
%G eng
%U http://arxiv.org/abs/0711.0397v2
%0 Journal Article
%J New Journal of Physics
%D 2007
%T Effective-range description of a Bose gas under strong one- or two-dimensional confinement
%A Pascal Naidon
%A Eite Tiesinga
%A William F. Mitchell
%A Paul S. Julienne
%X 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.
%B New Journal of Physics
%V 9
%P 19 - 19
%8 2007/01/29
%G eng
%U http://arxiv.org/abs/physics/0607140v2
%N 1
%! New J. Phys.
%R 10.1088/1367-2630/9/1/019
%0 Journal Article
%J Physical Review A
%D 2005
%T Multichannel quantum-defect theory for slow atomic collisions
%A Bo Gao
%A Eite Tiesinga
%A Carl J. Williams
%A Paul S. Julienne
%X 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.
%B Physical Review A
%V 72
%8 2005/10/28
%G eng
%U http://arxiv.org/abs/physics/0508060v1
%N 4
%! Phys. Rev. A
%R 10.1103/PhysRevA.72.042719
%0 Journal Article
%J Physical Review Letters
%D 2005
%T Spontaneous dissociation of long-range Feshbach molecules
%A Thorsten Koehler
%A Eite Tiesinga
%A Paul S. Julienne
%X 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$_2$.
%B Physical Review Letters
%V 94
%8 2005/1/18
%G eng
%U http://arxiv.org/abs/cond-mat/0408387v2
%N 2
%! Phys. Rev. Lett.
%R 10.1103/PhysRevLett.94.020402
%0 Journal Article
%J Journal of Physics B: Atomic, Molecular and Optical Physics
%D 2004
%T Adiabatic association of ultracold molecules via magnetic field tunable interactions
%A Krzysztof Goral
%A Thorsten Koehler
%A Simon A. Gardiner
%A Eite Tiesinga
%A Paul S. Julienne
%X 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.
%B Journal of Physics B: Atomic, Molecular and Optical Physics
%V 37
%P 3457 - 3500
%8 2004/09/14
%G eng
%U http://arxiv.org/abs/cond-mat/0312178v5
%N 17
%! J. Phys. B: At. Mol. Opt. Phys.
%R 10.1088/0953-4075/37/17/006
%0 Journal Article
%J Physical Review Letters
%D 2003
%T Ultracold collision properties of metastable alkaline-earth atoms
%A Andrei Derevianko
%A Sergey G. Porsev
%A Svetlana Kotochigova
%A Eite Tiesinga
%A Paul S. Julienne
%X 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.
%B Physical Review Letters
%V 90
%8 2003/2/13
%G eng
%U http://arxiv.org/abs/physics/0210076v1
%N 6
%! Phys. Rev. Lett.
%R 10.1103/PhysRevLett.90.063002