报告介绍 | Abstract: The recent implementation of orbital degrees of freedom in double-well optical lattices opens up a new avenue towards discovering novel quantum states of matter that have no prior analogues in solid-state electronic materials. In this talk, I will first give a brief review on some of the most exciting developments of optical lattice p-orbitals in both theory and experiment. Then, I will focus on two examples of topological order. One is a topological semimetal, characterized by a parabolic band-degeneracy point with Berry flux 2\pi due to the mixing of p and d orbital bands of a two-dimensional optical lattice. Another is the emergence of a Z_2 topological insulator of interacting fermions on a two-leg ladder of s and p orbitals, requiring none of the previously known mechanisms such as spin-orbit coupling, artificial gauge field, or p-wave pairing. The odd parity of p-orbitals is found key to both topological examples.
References: [1] M. Lewenstein and WVL, Nat. Phys. 7, 101 (2011); [2] K. Sun, WVL, A. Hemmerich, S. Das Sarma, Nat. Phys. 8, 6770 (2012); [3] X. Li, E. Zhao, WVL, arXiv:1205.0254.
Acknowledge support by ARO, AFOSR, and DARPA of the U.S. DOD, and A. Mellon Foundation. |