TY - JOUR
T1 - Photoassociation of spin polarized Chromium
JF - Physical Review A
Y1 - 2016
A1 - Jahn Rührig
A1 - Tobias Bäuerle
A1 - Paul S. Julienne
A1 - Eite Tiesinga
A1 - Tilman Pfau
AB - 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.
VL - 93
U4 - 021406
UR - http://arxiv.org/abs/1512.04378
CP - 2
U5 - 10.1103/PhysRevA.93.021406
ER -
TY - JOUR
T1 - Resonant control of polar molecules in an optical lattice
JF - Physical Review A
Y1 - 2012
A1 - Thomas M. Hanna
A1 - Eite Tiesinga
A1 - William F. Mitchell
A1 - Paul S. Julienne
AB - 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.
VL - 85
UR - http://arxiv.org/abs/1111.0227v1
CP - 2
J1 - Phys. Rev. A
U5 - 10.1103/PhysRevA.85.022703
ER -
TY - JOUR
T1 - Spatial separation in a thermal mixture of ultracold $^174$Yb and $^87$Rb atoms
JF - Physical Review A
Y1 - 2011
A1 - Florian Baumer
A1 - Frank Münchow
A1 - Axel Görlitz
A1 - Stephen E. Maxwell
A1 - Paul S. Julienne
A1 - Eite Tiesinga
AB - 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.
VL - 83
UR - http://arxiv.org/abs/1104.1722v1
CP - 4
J1 - Phys. Rev. A
U5 - 10.1103/PhysRevA.83.040702
ER -
TY - JOUR
T1 - Creation and manipulation of Feshbach resonances with radio-frequency radiation
JF - New Journal of Physics
Y1 - 2010
A1 - Thomas M. Hanna
A1 - Eite Tiesinga
A1 - Paul S. Julienne
AB - 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.
VL - 12
U4 - 083031
UR - http://arxiv.org/abs/1004.0636v1
CP - 8
J1 - New J. Phys.
U5 - 10.1088/1367-2630/12/8/083031
ER -
TY - JOUR
T1 - Collisional cooling of ultra-cold atom ensembles using Feshbach resonances
JF - Physical Review A
Y1 - 2009
A1 - L. Mathey
A1 - Eite Tiesinga
A1 - Paul S. Julienne
A1 - Charles W. Clark
AB - 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.
VL - 80
UR - http://arxiv.org/abs/0903.2568v1
CP - 3
J1 - Phys. Rev. A
U5 - 10.1103/PhysRevA.80.030702
ER -
TY - JOUR
T1 - Multi-channel modelling of the formation of vibrationally cold polar KRb molecules
JF - New Journal of Physics
Y1 - 2009
A1 - Svetlana Kotochigova
A1 - Eite Tiesinga
A1 - Paul S. Julienne
AB - 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.
VL - 11
U4 - 055043
UR - http://arxiv.org/abs/0901.1486v1
CP - 5
J1 - New J. Phys.
U5 - 10.1088/1367-2630/11/5/055043
ER -
TY - JOUR
T1 - Prediction of Feshbach resonances from three input parameters
JF - Physical Review A
Y1 - 2009
A1 - Thomas M. Hanna
A1 - Eite Tiesinga
A1 - Paul S. Julienne
AB - 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.
VL - 79
UR - http://arxiv.org/abs/0903.0884v2
CP - 4
J1 - Phys. Rev. A
U5 - 10.1103/PhysRevA.79.040701
ER -
TY - JOUR
T1 - Avoided crossings between bound states of ultracold Cesium dimers
JF - Physical Review A
Y1 - 2008
A1 - Jeremy M. Hutson
A1 - Eite Tiesinga
A1 - Paul S. Julienne
AB - 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.
VL - 78
UR - http://arxiv.org/abs/0806.2583v1
CP - 5
J1 - Phys. Rev. A
U5 - 10.1103/PhysRevA.78.052703
ER -
TY - JOUR
T1 - Two-body transients in coupled atomic-molecular BECs
JF - Physical Review Letters
Y1 - 2008
A1 - Pascal Naidon
A1 - Eite Tiesinga
A1 - Paul S. Julienne
AB - 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.
VL - 100
UR - http://arxiv.org/abs/0707.2963v2
CP - 9
J1 - Phys. Rev. Lett.
U5 - 10.1103/PhysRevLett.100.093001
ER -
TY - JOUR
T1 - Coherent, adiabatic and dissociation regimes in coupled atomic-molecular Bose-Einstein condensates
Y1 - 2007
A1 - Pascal Naidon
A1 - Eite Tiesinga
A1 - Paul S. Julienne
AB - 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.
UR - http://arxiv.org/abs/0711.0397v2
ER -
TY - JOUR
T1 - Effective-range description of a Bose gas under strong one- or two-dimensional confinement
JF - New Journal of Physics
Y1 - 2007
A1 - Pascal Naidon
A1 - Eite Tiesinga
A1 - William F. Mitchell
A1 - Paul S. Julienne
AB - 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.
VL - 9
U4 - 19 - 19
UR - http://arxiv.org/abs/physics/0607140v2
CP - 1
J1 - New J. Phys.
U5 - 10.1088/1367-2630/9/1/019
ER -
TY - JOUR
T1 - Multichannel quantum-defect theory for slow atomic collisions
JF - Physical Review A
Y1 - 2005
A1 - Bo Gao
A1 - Eite Tiesinga
A1 - Carl J. Williams
A1 - Paul S. Julienne
AB - 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.
VL - 72
UR - http://arxiv.org/abs/physics/0508060v1
CP - 4
J1 - Phys. Rev. A
U5 - 10.1103/PhysRevA.72.042719
ER -
TY - JOUR
T1 - Spontaneous dissociation of long-range Feshbach molecules
JF - Physical Review Letters
Y1 - 2005
A1 - Thorsten Koehler
A1 - Eite Tiesinga
A1 - Paul S. Julienne
AB - 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$_2$.
VL - 94
UR - http://arxiv.org/abs/cond-mat/0408387v2
CP - 2
J1 - Phys. Rev. Lett.
U5 - 10.1103/PhysRevLett.94.020402
ER -
TY - JOUR
T1 - Adiabatic association of ultracold molecules via magnetic field tunable interactions
JF - Journal of Physics B: Atomic, Molecular and Optical Physics
Y1 - 2004
A1 - Krzysztof Goral
A1 - Thorsten Koehler
A1 - Simon A. Gardiner
A1 - Eite Tiesinga
A1 - Paul S. Julienne
AB - 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.
VL - 37
U4 - 3457 - 3500
UR - http://arxiv.org/abs/cond-mat/0312178v5
CP - 17
J1 - J. Phys. B: At. Mol. Opt. Phys.
U5 - 10.1088/0953-4075/37/17/006
ER -
TY - JOUR
T1 - Ultracold collision properties of metastable alkaline-earth atoms
JF - Physical Review Letters
Y1 - 2003
A1 - Andrei Derevianko
A1 - Sergey G. Porsev
A1 - Svetlana Kotochigova
A1 - Eite Tiesinga
A1 - Paul S. Julienne
AB - 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.
VL - 90
UR - http://arxiv.org/abs/physics/0210076v1
CP - 6
J1 - Phys. Rev. Lett.
U5 - 10.1103/PhysRevLett.90.063002
ER -