Bulletin of the American Physical Society
47th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 61, Number 8
Monday–Friday, May 23–27, 2016; Providence, Rhode Island
Session B3: Focus Session: Quantum Gases with Dipolar InteractionsFocus
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Chair: Bill Stwalley, University of Connecticut Room: Ballroom D |
Tuesday, May 24, 2016 10:30AM - 11:00AM |
B3.00001: Exploring Few- and Many-Body Dipolar Quantum Phenomena with Ultracold Erbium Atoms Invited Speaker: Francesca Ferlaino Given their strong magnetic moment and exotic electronic configuration, rare-earth atoms disclose a plethora of intriguing phenomena in ultracold quantum physics with dipole-dipole interaction. Here, we report on the first degenerate Fermi gas of erbium atoms, based on direct cooling of identical fermions via dipolar collisions. We reveal universal scattering laws between identical dipolar fermions close to zero temperature, and we demonstrate the long-standing prediction of a deformed Fermi surface in dipolar gas. Finally, we present the first experimental study of an extended Bose-Hubbard model using bosonic Er atoms in a three-dimensional optical lattice and we report on the first observation of nearest-neighbor interactions. [Preview Abstract] |
Tuesday, May 24, 2016 11:00AM - 11:30AM |
B3.00002: Novel states of matter with ultracold magnetic lanthanides Invited Speaker: Svetlana Kotochigova Ultracold atomic physics is now poised to enter a new regime, where far-more complex atomic species can be cooled and studied. Magnetic lanthanide atoms with their large magnetic moment and large orbital momentum are extreme examples of such species. In fact, ultracold gases of magnetic lanthanides provide the opportunity to examine strongly correlated matter, creating a platform to explore exotic many-body phases such as quantum ferrofluids, quantum liquid crystals, and supersolids. Experimental advances in trapping and cooling magnetic Dy and Er atoms are paving the way towards these goals. Over the last few years we have developed a framework for understanding the complex anisotropic interactions between magnetic lanthanide atoms. Our theoretical model uses novel tools and advanced numerical treatments to describe the underlying mechanism that generates correlations and chaos in dipolar scattering and bridges the enormous conceptual gap between simple atoms and complex molecules. This allows us to explain the origin of the dense spectra and statistics of the observed Er and Dy collisional resonances due to the anisotropy of the short- and long-range interactions between the atoms. We also study the distribution of the values of the molecular wave functions to isolate Anderson-type localized states within chaotic structures and confirm the existence of an intermediate chaotic regime. In addition, our model for the three-body recombination via the formation of a resonant trimer has identified the origin of the temperature-sensitive resonance density observed in both Er and Dy collisions as due to d-wave entrance channel collisions. [Preview Abstract] |
Tuesday, May 24, 2016 11:30AM - 11:42AM |
B3.00003: Broad Feshbach resonances in collisions of Dy atoms P Julienne, K Jachymski, T Maier, I Ferrier-Barbut, H Karan, M Schmitt, M Wenzel, C Wink, T Pfau RF spectroscopy of weakly bound dimers of ultra cold bosonic Dy atoms gives evidence for the emergence of a universal s-wave halo state in a background of chaotic background resonance states. The halo state is associated with a broad magnetic Feshbach resonance. Using a coupled channels theory taking into account the short ranged van dear Waals interaction and a correction due to the strong dipole moment of Dy, we are able to extract the scattering length as a function of magnetic field tuning near two such broad resonances. These results offer prospects for tuning the interactions of Dy atoms in a regime where three-body losses are not too strong. [Preview Abstract] |
Tuesday, May 24, 2016 11:42AM - 11:54AM |
B3.00004: From dipolar to multipolar interactions between ultracold Feshbach molecules Goulven Qu{\'e}m{\'e}ner, Maxence Lepers, Eliane Luc-Koenig, Olivier Dulieu Using the multipolar expansion of electrostatic and magnetostatic potential energies, we characterize the long-range interactions between two weakly-bound diatomic molecules [1], taking as an example the paramagnetic Er$_2$ Feshbach molecules which were produced recently [2]. The interaction between atomic magnetic dipoles gives rise to the usual $R^{-3}$ leading term of the multipolar expansion, where $R$ is the intermolecular distance. We show that additional terms scaling as $R^{-5}$, $R^{-7}$ and so on also appear, which are strongly anisotropic with respect to the orientation of the molecules. These terms can be seen as effective molecular multipole moments reflecting the spatial extension of the molecules which is non-negligible compared to $R$. [1] M. Lepers, G. Qu{\'e}m{\'e}ner, E. Luc-Koenig, O. Dulieu, J. Phys. B: At. Mol. Opt. Phys. 49, 014004 (2016) ; [2] A. Frisch, M. Mark, K. Aikawa, S. Baier, R. Grimm, A. Petrov, S. Kotochigova, G. Qu{\'e}m{\'e}ner, M. Lepers, O. Dulieu, F. Ferlaino, Phys. Rev. Lett. 115, 203201, (2015). [Preview Abstract] |
Tuesday, May 24, 2016 11:54AM - 12:06PM |
B3.00005: Quantum Monte Carlo study of entanglement entropy for dipolar hardcore bosons in optical lattices Wei Wang, Arghavan Safavi-Naini, Barbara Capogrosso-Sansone Entanglement entropy and its scaling with system size provide an alternative way to characterize quantum phases and phase transitions, and can be used to probe topological order. Motivated by the recent theoretical investigation of entanglement properties of the ground-states of hard-core lattice bosons, we use Quantum Monte Carlo simulations, well suited to studying equilibrium properties, to calculate the Renyi entropy and topological entanglement entropy of the ground state of dipolar lattice bosons. In contrast to the traditional observables, these probes allow us to study the emergence of long-range entanglement in the ground state, as well as its dependence on the dipolar coupling. Additionally, in light of recent experimental success in creating low entropy dipolar lattice gases we discuss the possibility of observing these phases experimentally. [Preview Abstract] |
Tuesday, May 24, 2016 12:06PM - 12:18PM |
B3.00006: Collisional effects in the dynamics of a dipolar gas Andrew Sykes In this talk, we discuss the role of collisions in dipolar gases which are far from equilibrium. We compare and contrast collisional mechanisms with mean-field effects. We consider several cases of dynamical behaviour. We begin with cross-dimensional relaxation, where the time-scale of equilibration is studied following a quench in the trap parameters. We also discuss the damping of monopole and quadrupole excitations. Finally we discuss time-of-flight expansion dynamics. Our results demonstrate that collisions can play a significant role. We use these results to extract an estimate of the deca-heptuplet s-partial-wave scattering length of bosonic dysprosium, and to improve the accuracy of experimental time-of-flight expansion imaging. [Preview Abstract] |
Tuesday, May 24, 2016 12:18PM - 12:30PM |
B3.00007: Ultracold Dysprosium Gas Chayma Bouazza Ultracold quantum gases with long-rang and anisotropic interactions open the door to new possibilities for exploring correlated many-body systems. The advantage of using ultracold atoms in order to realize such systems relies on the high level of control and manipulation offered by this field. Recent progress in trapping and cooling some Lanthanide atoms with a strong magnetic moment such as Erbium or Dysprosium present an important tool to investigate the dipole-dipole interaction. \\In particular the dysprosium atom has multiple features that make it an interesting candidate to study such systems. It has the largest magnetic moment among all atoms ($10 \mu_B$) and a rich energy level structure which allows the implementation of different cooling schemes. \\In my talk I will present our experiment with the bosonic isotope $^{164}$Dy. I will set forth the interesting features of Dysprosium and explain the difference with alkali systems. [Preview Abstract] |
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