© 2019 American Physical Society. We study the single-particle properties of a system formed by ultracold atoms loaded into the manifold of l=1 orbital angular momentum (OAM) states of an optical lattice with a diamond-chain geometry. 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 π flux through the plaquettes. These effects give rise to a topologically nontrivial band structure and protected edge states which persist everywhere in the parameter space of the model, indicating the absence of a topological transition. By taking advantage of these analytical mappings, we also show that this system constitutes a realization of a square-root topological insulator. In addition, we demonstrate that quantum interferences between the different tunneling processes involved in the dynamics may lead to Aharanov-Bohm caging in the system. All these analytical results are confirmed by exact diagonalization numerical calculations.
Pelegrí, G., Marques, A. M., Dias, R. G., Daley, A. J., Ahufinger, V., & Mompart, J. (2019). Topological edge states with ultracold atoms carrying orbital angular momentum in a diamond chain. Physical Review A, 99, . https://doi.org/10.1103/PhysRevA.99.023612