Mainz 2017 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 52: Quantum Gases: Fermions II
Q 52.7: Vortrag
Donnerstag, 9. März 2017, 16:00–16:15, P 204
Measurement of the merging transition of Dirac points in a tunable optical lattice — •Matthias Tarnowski1,3, Marlon Nuske2, Nick Fläschner1,3, Benno Rem1,3, Dominik Vogel1, Klaus Sengstock1,2,3, Ludwig Mathey1,2,3, and Christof Weitenberg1,3 — 1Institut für Laserphysik, Universität Hamburg, 22761 Hamburg, Germany — 2Zentrum für optische Quantentechnologien, Universität Hamburg, 22761 Hamburg, Germany — 3The Hamburg Centre for Ultrafast Imaging, 22761 Hamburg, Germany
Topological defects, such as Dirac points in graphene, and their resulting Berry phases play an important role, e.g. for the electronic dynamics in solid state crystals. Tunable quantum gas systems in optical lattices allow for deep and new insights into topological properties of quantum many-body systems. Here we discuss the experimental observation of the so-called merging transition of Dirac points in a tunable hexagonal optical lattice in a boron nitride configuration. We have developed a new method to fully map out the positions of the topological defects in a two-band model. Our measurements illustrate that topological defects are robust under change of lattice parameters and can only be destroyed by annihilation of two vortices with opposite winding.