| 报告题目 | Strongly correlated and t opological orbital physics in the honeycomb lattice – a novel artificial material in optical lattices |
| 报告人 | Prof. Congjun Wu |
| 报告人单位 | University of California, San Diego |
| 报告时间 | 2013-08-07 |
| 报告地点 | 合肥微尺度物质科学国家实验室九楼会议室 |
| 主办单位 | 合肥微尺度物质科学国家实验室、国际功能材料量子设计中心 |
| 报告介绍 | 报告摘要：
Orbital is a degree of freedom independent of charge and spin, which is characterized by spatial anisotropy and orbital degeneracy. It plays an important role in magnetism, superconductivity, and transport in transition metal oxides. Recently, the ultra-cold atom optical lattice has provided a new opportunity to investigate novel orbital physics that does not appear in usual solid state systems. For example, compared to d and f-orbitals, p-orbital is unidirectional and thus more anisotropic. However, most p-orbital solid state materials are semiconductors in which correlation effects are weak. In contrast, the p-orbital bands in optical lattice can integrate strong correlations and strong anisotropy closely. In this talk, we will focus on the p$_{x,y}$ orbital physics in the 2D honeycomb optical lattice. In contrast, graphene is not an orbitally active material. Interesting physics here includes the flat band structure and the consequential non-perturbative strong correlation effects (e.g. Wigner crystal and ferromagnetism). In the Mott-insulating state, orbital exchange is highly frustrated described by a quantum120$^\circ$ model in a similar form to the celebrated Kitaev model. The current available experimental technique of orbital angular momentum polarization can naturally realize Haldane’s quantum anomalous Hall model. We will show that an f-wave Cooper pairing arises with boundary Majorana modes. Although the pairing mechanism is conventional, the unconventional pairing symmetry is driven by the non-trivial band structure. We will also show the connection between the above physics in optical lattices with the recent progress in solid state materials.
报告人简介：
Congjun Wu received his Ph.D. in physics from Stanford University in 2005, and did his postdoctoral research at the Kavli Institute for Theoretical Physics, University of California, Santa Barbara, from 2005 to 2007. He became an assistant professor in the Department of Physics at the University of California, San Diego (UCSD) in 2007, and an associate professor at UCSD in 2011. His research interests include quantum magnetism, superconductivity, orbital physics, and topological states in condensed-matter and cold-atom systems. |
