Mainz 2017 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 21: Ultracold atoms and BEC - IV (with Q)
A 21.3: Vortrag
Mittwoch, 8. März 2017, 15:00–15:15, N 1
Exotic energy bands and topological phases in systems with oscillatory long-range potentials — Beatriz Olmos Sánchez1,2, Robert J. Bettles3, Igor Lesanovsky1,2, and •Jiří Minář1,2 — 1School of Physics and Astronomy, University of Nottingham, United Kingdom — 2Centre for the Mathematics and Theoretical Physics of Non-equilibrium Quantum Systems, University of Nottingham, United Kingdom — 3Joint Quantum Center (JQC) Durham-Newcastle, Department of Physics, Durham University, United Kingdom
The effective interaction between neutral atoms mediated by virtual photon exchange in general leads to a non-trivial long-range potential featuring both attractive and repulsive interaction [1,2] which goes beyond the typically considered simple power-law (dipolar, Van der Waals) potentials. Considering the full potential in two dimensions (which becomes relevant for atomic separations comparable to the atomic transition wavelength, situation achievable e.g. with strontium atoms), we show that it gives rise to energy spectrum with one-sided divergences in the Brillouin zone. This apparently unphysical situation is a consequence of the superextensivity of the potential and the thermodynamic limit. We perform a study for finite size systems and find new topological phases absent in the dipolar case. Moreover, the shape of the potential leads to a novel situation where energy peaks in the spectrum of arbitrary height and position can be created. Finally, we discuss the relation between the bulk and the edge states in case of square and hexagonal lattice. [1] R. H. Lehmberg, Phys. Rev. A 2 883 (1970), [2] D. F. V. James, Phys. Rev. A 47 1336 (1993)