Research interests:
- Many-body properties of strongly interacting Fermi and Bose gases
- Ultracold collisions and analytic properties of resonant interactions
- Few-body physics
- Strong interactions in optical lattices
- Ultracold plasmas
and Rydberg lattices
We participate in the International
Cold Atom Network.
We are part of the POLATOM ESF
Research Networking Programme.
In the department we participate in the Network Theoretical Physics.
Our research project atomic gases with strong interactions was funded by an NWO-VIDI grant.
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Latest News:
Creation
of Rydberg Crystals
Ultracold
atomic gases have been used extensively in recent years to realize
textbook examples of condensed matter phenomena. Recently, phase
transitions to ordered structures have been predicted for gases of
highly excited, 'frozen' Rydberg atoms. Such Rydberg crystals are a
model for dilute metallic solids with tunable lattice parameters, and
provide access to a wide variety of fundamental phenomena. We
investigate theoretically how such structures can be created in four
distinct cold atomic systems, by using tailored laser-excitation in the
presence of strong Rydberg-Rydberg interactions. We study in detail the
experimental requirements and limitations for these systems, and
characterize the basic properties of small crystalline Rydberg
structures in one, two and three dimensions:
arXiv:1103.2096
Collapsing Bose-Einstein Condensates
We describe a model of dynamic Bose-Einstein condensates near a Feshbach resonance that is computationally feasible under assumptions of spherical or cylindrical symmetry. Simulations in spherical symmetry approximate the experimentally measured time to collapse of an unstably attractive condensate, suggesting that the quantum fluctuations and atom-molecule pairing included in the model are the dominant mechanisms during collapse. Simulations of condensates with repulsive interactions find some quantitative disagreement, suggesting that pairing and quantum fluctuations are not the only significant factors for condensate loss or burst formation. Inclusion of three-body recombination was found to be inconsequential in all of our simulations: arXiv:1102.2104Efimov Trimers in a Harmonic Potential
We study the Efimov effect in a harmonic oscillator in the hyperspherical formulation, and show how a reduced model allows for a description that is a generalization of the Efimov effect in free space and leads to results that are easily interpreted. Efimov physics may be observed by varying the value of the scattering length, since in the regime where the trimers have a mixed harmonic oscillator and Efimov character, the inelastic properties of these states are still manageable. The model also allows for the study of non-universal Efimov trimers by including the effective range scattering parameter. While we find that in a certain regime the effective range parameter can take over the role of the three-body parameter, interestingly, we obtain a numerical relationship between these two parameters different from what was found in other models: arXiv:1101.0696