报告题目：Frustrated optical lattice: from topological excitations to deconfined phase transition

报告人：张学峰 助教授

重庆大学

报告时间：11月17日（周五）下午3:00

报告地点：理论物理研究所报告厅

We analyzed the repulsive particles in the frustrated optical lattice. For the triangular lattice, we find two co-order exist phases: supersolid [1] and ordered metals [2]. Both behave like fluid but also keep crystal structure. After introducing the spatial anisotropy, the bosonic domain walls are excited. Such topological defects can continuously change the crystal structure, so that the exotic incommensurate supersolid is observed [3].

Similar phenomena can also be found in the kagome optical lattice. When choosing cylindrical boundary condition, we found a novel edge liquid phase with fractional charges (spinons) linked by quantum strings (effective gauge field) [4]. In the strong coupling limit, we obtained the effective lattice gauge field theory which shows easy-plane NCCP1 form. And it hints the phase transition from valence bond solid to superfluid can be continuous one which is beyond Ginzburg-Landau symmetry breaking diagram. Recently, such topological phase transition is verified by utilizing large scale quantum Monte Carlo simulations [5].

[1] X.-F. Zhang, R. Dillenschneider, Y. Yu, and S. Eggert, Phys. Rev. B 84, 174515 (2011)

[2] L.-F. Tocchio, C. Gros, X.-F. Zhang, and S. Eggert, Phys. Rev. Lett. 113, 246405 (2014)

[3] X.-F. Zhang, S.-J. Hu, A. Pelster, and S. Eggert, Phys. Rev. Lett. 117, 193201 (2016)

[4] X.-F. Zhang and S. Eggert, Phys. Rev. Lett. 111, 147201 (2013)

[5] X.-F. Zhang, Y.-C. He, S. Eggert, R. Moessner, and F. Pollmann, arXiv 1706.05414

  

 

张学锋

博士，博士生导师, 重庆大学“**”助教授 

邮件：zhangxf@cqu.edu.cn

 

教育背景：

2002-2006 山西大学物理学（国家基地）

2006-2011 中国科学院理论物理所硕博连读生

2008-2010 德国凯泽斯劳腾理工大学联合培养（DAAD-CAS奖学金）

 

工作经历： 

2011-2015 德国凯泽斯劳腾理工大学博士后

2015-2017 德国马克斯普朗克研究所博士后

2017-至今 重庆大学“**”助教授

 

研究方向：

我们主要关心强关联系统中的新奇相以及相关的相变过程，利用大规模数值计算方法对系统进行模拟，例如量子蒙特卡罗，精确对角化以及密度矩阵重整化群等方法。同时，我们也利用平均场，微扰论以及有效场论等解析方法来理解背后的物理机制。