title: Topological Varma Superfluid in Optical Lattices.
abstract: Topological states of matter are peculiar quantum phases showing different edge and bulk transport properties connected by the bulk-boundary correspondence. While noninteracting fermionic topological insulators are well established by now and have been classified according to a tenfold scheme, the possible realization of topological states for bosons has not been explored much yet. Furthermore, the role of interactions is far from being understood. Here, we show that a topological state of matter exclusively driven by interactions may occur in the p band of a Lieb optical lattice filled with ultracold bosons. The single-particle spectrum of the system displays a remarkable parabolic band-touching point, with both bands exhibiting non-negative curvature. Although the system is neither topological at the single-particle level nor for the interacting ground state, on-site interactions induce an anomalous Hall effect for the excitations, carrying a nonzero Chern number. Our work introduces an experimentally realistic strategy for the formation of interaction-driven topological states of bosons.
authors: Institute for Theoretical Physics, Centre for Extreme Matter and Emergent Phenomena, Utrecht University, Leuvenlaan 4, 3584CE Utrecht, The Netherlands.|INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, 38123 Povo, Italy.
authors: M
authors: M
authors: Di Liberto
authors: Institut für Laser-Physik, Universität Hamburg, LuruperChaussee 149 22761 Hamburg, Germany.|The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg, Germany.|Wilczek Quantum Center, Zhejiang University of Technology, Hangzhou 310023, China.
authors: A
authors: A
authors: Hemmerich
authors: Institute for Theoretical Physics, Centre for Extreme Matter and Emergent Phenomena, Utrecht University, Leuvenlaan 4, 3584CE Utrecht, The Netherlands.|Wilczek Quantum Center, Zhejiang University of Technology, Hangzhou 310023, China.
authors: C
authors: C
authors: Morais Smith