刘雄军 教授；北京大学

　　题目：Quantum simulation for Rydberg atoms with laser-assisted dipole-dipole interactions

　　时间：2023年5月13日 下午 14:00

　　地点：惟真楼2楼219

　　摘要：Rydberg atoms with dipole-dipole interactions and arranged in arrays provide intriguing platforms to explore exotic quantum many-body physics. In this talk, following a pedagogic introduction to the Rydberg atoms, I will present a novel mechanism that we proposed recently, dubbed laser-assisted dipole-dipole interactions, to realize synthetic gauge fields and correlated topological states for Rydberg atom arrays. In the presence of an energy offset between neighboring Rydberg atoms, the bare dipole-dipole interaction between them is suppressed, but an effective dipole-dipole interaction can be assisted when Raman lights are applied to compensate the energy difference. With this scheme we are able to simulate various novel correlated quantum matters. In particular, we first achieve a feasible scheme to generate tunable synthetic gauge fields for the complex spin-exchange coupling model, which realizes the highly tunable flat Chern bands of the hard core bosons are obtained and further, the bosonic fractional quantum Hall states. Moreover, the laser-assisted dipole-dipole interaction can be broadly applied to various Rydberg atom array configurations, particularly the Raman superarrays of Rydberg atoms. In the Rydberg superarray of 1D ladder configuration, we show an exactly solvable model which hosts the exotic quantum critical states. In the 2D case, we propose a novel stripe lattice model to realize a fractional quantum anomalous Hall phase, with the manipulation and detection via correlated quench dynamics being introduced and discussed.

　　刘雄军教授2011年于德州A&M大学获博士学位。之后分别在马里兰大学，香港科大高等研究院及麻省理工学院从事博士后研究。他2014年9月加入北大量子材料中心任研究员，入选国家人才项目。2018年7月获长聘，同年8月获得国家杰青资助，2019年1月晋升正教授、北大博雅特聘教授。刘雄军长期在拓扑超导等拓扑物相和超冷原子量子模拟领域开展研究，取得一系列原创和引领性成果，获得2019年亚太物理学会和亚太理论物理中心“杨振宁奖（CN Yang Award）”等荣誉。发迄今表论文80余篇，包括Science, Science子刊，Nature Physics, PRL, PRX等权威期刊40余篇。

　　李有泉 教授；南开大学

　　题目：Manipulation of Skyrmions and the Promising Applications

　　时间：2023年5月13日 下午 14:00

　　地点：新综合楼2楼219

　　摘要：There has been spectacular progress in the study on multiferroics, which is expected to make a realistic step toward an electrical control of magnetism or four state memories. We propose a tilted Heisenberg model of which the continuum limit is a gauge Landau-Lifshitz equation that provides a unified description for various exotic spin orders appeared. For certain gauge potential, we solved the magnetic skyrmion phase and also predicted the emergence of meron phase. We also propose a mechanism to pin skyrmions in chiral magnet, and find that the position-dependent electric field can induce the Hall motion of the skyrmion. Furthermore, we study spin-orbital driven ferroelectricity; spin-orbital coupling and charge effect in Mott insulators showing that the tilted Heisenberg model can be derived from the Hubbard model in the presence of spin-orbital coupling as the large U limit. The idea of tilted Heisenberg model has been extended to the SU(3) case by experts working on high-energy physics recently. Moreover, we show that in the stationary regime the chirality of the domain wall can be efficiently reversed when the electric field is applied along the direction of the magnetic field. These characteristics suggest that the multiferroic domain wall may provide a new prospective means to design faster and low-power-consumption domain wall devices. These results are expected to motivate experimentalists to prepare new type of multiferroics material or design new spintronics device.

　　李有泉，教授、博导，长期从事理论凝聚态物理研究工作，发表论文160余篇；主持国家自然科学基金13项、国家重点研发计划项目1项；获国家自然科学二等奖1项、中国高校自然科学一等奖1项；入选“教育部长江学者”，“新世纪百千万人才工程”国家级人选“国家万人计划”--百千万工程领军人才；获全国“五一”劳动奖章、留学回国人员成就奖章及第八届中国青年科技奖；曾任《科学通报》、《Frontiers of Physics》、《物理学进展》等期刊编委，现任中国物理学会秋季会议、全国磁学理论会议等组委会委员。