Rostock 2019 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 60: Quantum Gases (Bosons and Fermions) II
Q 60.4: Vortrag
Freitag, 15. März 2019, 11:30–11:45, S HS 037 Informatik
Direct measurement of density-dependent Peierls phases in a driven Hubbard dimer — •Konrad Viebahn, Frederik Görg, Kilian Sandholzer, Joaquín Minguzzi, Rémi Desbuquois, Michael Messer, and Tilman Esslinger — Institute for Quantum Electronics, ETH Zurich, CH-8093 Zurich
The coupling between gauge and matter fields is a key concept in many models of high-energy and condensed matter physics. In these models the gauge fields are dynamical quantum degrees of freedom, i.e. they are influenced by the spatial configuration and motion of the matter field. It has been proposed to implement this coupling mechanism on quantum simulation platforms, ultimately aiming at emulating lattice gauge theories. However, existing methods for generating gauge fields in optical lattices lack the back-action from the atoms. In this experiment we realise the fundamental ingredient for a density-dependent gauge field by engineering non-trivial Peierls phases that depend on the site occupation of fermions in a Hubbard dimer. Our method relies on breaking time-reversal symmetry (TRS) by driving an optical super-lattice simultaneously at two frequencies, at resonance with the on-site interaction. In addition, a constant energy offset between the two sites of the double-well allows us to single out one tunnelling process of which we characterise both the amplitude and the associated Peierls phase. When TRS is not broken the phase exhibits a sudden jump of exactly π, characterised by a Z2-invariant. For the general case, we determine the winding structure of the Peierls phase which features a Dirac point as a function of driving parameters.