Title: Weyl Semimetals in 3D Optical Lattices, and Synthetic Gauge Fields in Strongly Interacting 1D Bose Gases.
When: Friday, November 25, (2016), 12:00.
Place: Departamento de Física Teórica de la Materia Condensada, Facultad Ciencias, Module 5, Seminar Room (5th Floor).
Speaker: Hrvoje Buljan, Department of Physics, Faculty of Science, University of Zagreb, Bijenička c. 32, 10000 Zagreb, Croatia.
We discuss two important directions of research of synthetic topological quantum matter : (i) topological phases in 3D optical lattices, more specifically Weyl semimetals in ultracold atomic gases , and (ii) strongly interacting Bose gases in synthetic gauge fields . Interacting Bose gases in synthetic magnetic fields  hold great potential for discovering and exploring novel topological states of matter , in a similar fashion as the fractional quantum Hall effect for electrons in strong magnetic fields. Here we investigate laser assisted tunneling in a strongly interacting one-dimensional Bose gas  (the Tonks-Girardeau gas ) in optical lattices. We find that the stroboscopic dynamics of the Tonks-Girardeau gas in a continuous Wannier-Stark-ladder potential, supplemented with laser assisted tunneling, effectively realizes the ground state of one-dimensional hardcore bosons in a discrete lattice  with nontrivial hopping phases. Next, we show that, in three-dimensional optical lattices, laser assisted tunneling can be used for realizing a Hamiltonian with Weyl points . Weyl points are synthetic magnetic monopoles that exhibit a robust, three-dimensional linear dispersion, identical to the energy-momentum relation for relativistic Weyl fermions , which are not yet discovered in particle physics. Relation to analogous studies in optics will be mentioned .
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