Ultracold atoms carrying orbital angular momentum in lattices of rings: topology and quantum magnetism ( Prof. Veronica Ahufinger)
Ultracold atoms carrying orbital angular momentum in lattices of rings: topology and quantum magnetism
- Datum: 14.01.2020
- Uhrzeit: 14:30
- Vortragende(r): Prof. Verònica Ahufinger
- Universitat Autònoma de Barcelona, Spain
- Ort: Max Planck Institute of Quantum Optics
- Raum: Herbert Walther Lecture Hall
In the context of topology, we study the single-particle properties of a system formed by ultracold atoms loaded into the manifold of one unit of OAM states of an optical lattice with a diamond chain geometry [1,2]. Through a series of successive basis rotations, we show that the OAM degree of freedom induces phases in some tunneling amplitudes of the tight-binding model that are equivalent to a net p flux through the plaquettes and give rise to a topologically non-trivial band structure and protected edge states. In addition, we demonstrate that the system exhibits Aharanov-Bohm caging. In two dimensional (2D) lattices, we also propose a realization of a 2D high order topological insulator . We describe the system in terms of two decoupled lattice models, each of them displaying one-dimensional edge states and zero-dimensional corner states that are correlated with the topological properties of the bulk. We show that this topologically non-trivial regime can be explored in a wide range of experimentally feasible values of the parameters of the physical system. Furthermore, we propose an alternative way to characterize the second-order topological corner states based on the computation of the Zak's phases of the bands of first-order edge states.
In the Mott insulator limit, we focus on unit filling, where each trap is occupied by a single atom and a direct mapping between the OAM and spin-1/2 states can be performed . We consider explicitly the dependence of the effective couplings on the geometry of the system and demonstrate that several models of interest related to a general XYZ Heisenberg model with an external field can be obtained. Furthermore, we discuss how the relative strength of the effective couplings can be tuned and which phases can be explored by doing so in realistic setups.
 G. Pelegrí, A. M. Marques, R. G. Dias, A. J. Daley, V. Ahufinger and J. Mompart, Topological edge states with ultracold atoms carrying orbital angular momentum in a diamond chain. Phys. Rev. A 99, 023612 (2019).
 G. Pelegrí, A. M. Marques, R. G. Dias, A. J. Daley, J. Mompart and V. Ahufinger, Topological edge states and Aharanov-Bohm caging with ultracold atoms carrying orbital angular momentum. Phys. Rev. A 99, 023613 (2019).
 G. Pelegrí, A. M. Marques, V. Ahufinger, J. Mompart, and R. G. Dias, Second-order topological corner states with ultracold atoms carrying orbital angular momentum in optical lattices, submitted to Phys. Rev. B.
 G. Pelegrí, J. Mompart, V. Ahufinger, A. J.
Daley, Quantum magnetism with ultracold bosons carrying orbital angular
momentum, Phys. Rev. A 100, 023615