



@article {2000,
	title = {Above threshold scattering about a Feshbach resonance for ultracold atoms in an optical collider},
	journal = {Nature Communications},
	volume = {8},
	year = {2017},
	month = {2017/09/06},
	abstract = {<p>Studies of magnetically tunable Feshbach resonances in ultracold atomic gases have predominantly been carried out in the zero collision-energy limit. Here, we explore above threshold collisions at well-defined energies in the vicinity of a narrow magnetic Feshbach resonance by means of a laser-based collider. Our experiment focuses on collisions between ground-state 87Rb atoms in the |F = 2,mF = 0i and |F = 1,mF = 1i hyperfine states, which have a known s-wave resonance at 9.040(7) G at threshold that strongly couples to inelastic channels, where 1 G = 10\&minus;4 T. Using our collider we can track the magnetic field shift in resonance position as the energy is tuned. This presents a challenge due to the narrow width of the resonance in conjunction with inherent broadening mechanisms of the collider. We find, however, that the narrow Feshbach scattering feature becomes imprinted on the spatial distribution of atoms in a fashion that allows for an accurate determination of resonance position as a function of collision energy through a shift in center-of-mass position of the outgoing clouds. This shift has a dispersive line shape with a zero value at the resonance position. We obtain excellent agreement with theory on the resonance position.</p>},
	doi = {10.1038/s41467-017-00458-y},
	url = {https://arxiv.org/abs/1704.07109},
	author = {Milena S. J. Horvath and Ryan Thomas and Eite Tiesinga and Amita B. Deb and Niels Kj{\ae}rgaard}
}
@article {1279,
	title = {Anisotropy induced Feshbach resonances in a quantum dipolar gas of  magnetic atoms
},
	journal = {Physical Review Letters},
	volume = {109},
	year = {2012},
	month = {2012/9/7},
	abstract = {  We explore the anisotropic nature of Feshbach resonances in the collision
between ultracold magnetic submerged-shell dysprosium atoms, which can only
occur due to couplings to rotating bound states. This is in contrast to
well-studied alkali-metal atom collisions, where most Feshbach resonances are
hyperfine induced and due to rotation-less bound states. Our novel
first-principle coupled-channel calculation of the collisions between
open-4f-shell spin-polarized bosonic dysprosium reveals a striking correlation
between the anisotropy due to magnetic dipole-dipole and electrostatic
interactions and the Feshbach spectrum as a function of an external magnetic
field. Over a 20 mT magnetic field range we predict about a dozen Feshbach
resonances and show that the resonance locations are exquisitely sensitive to
the dysprosium isotope.
},
	doi = {10.1103/PhysRevLett.109.103002},
	url = {http://arxiv.org/abs/1203.4172v1},
	author = {Alexander Petrov and Eite Tiesinga and Svetlana Kotochigova}
}
@article {1283,
	title = {Avoided crossings between bound states of ultracold Cesium dimers},
	journal = {Physical Review A},
	volume = {78},
	year = {2008},
	month = {2008/11/5},
	abstract = {  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.
},
	doi = {10.1103/PhysRevA.78.052703},
	url = {http://arxiv.org/abs/0806.2583v1},
	author = {Jeremy M. Hutson and Eite Tiesinga and Paul S. Julienne}
}
@article {1288,
	title = {Adiabatic association of ultracold molecules via magnetic field tunable  interactions
},
	journal = {Journal of Physics B: Atomic, Molecular and Optical Physics},
	volume = {37},
	year = {2004},
	month = {2004/09/14},
	pages = {3457 - 3500},
	abstract = {  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.
},
	doi = {10.1088/0953-4075/37/17/006},
	url = {http://arxiv.org/abs/cond-mat/0312178v5},
	author = {Krzysztof Goral and Thorsten Koehler and Simon A. Gardiner and Eite Tiesinga and Paul S. Julienne}
}
