报告题目：Ultracold Quantum Matter in a Hubbard Simulator

报告人：杨兵 助理教授（南方科技大学）

报告时间：2021年12月23日（周四）下午5点

报告地点：光电所二层报告厅

报告摘要：

      Ultracold neutral atoms in optical lattices form a Hubbard quantum simulator for studying many-body physics. In recent years, we scale up the quantum correlations between bosonic particles in this simulator from the basic 2-site building block to a 71-site many-body system. These achievements are enabled by a series of experimental advances including preparation of a low-entropy sample, manipulation of atomic spins and probing many-body correlations. Using an optical superlattice, we generated and detected the quantum entanglement of Bell pairs and verify its violation of Bell inequality. In 4-site square plaquettes, we observed the four-body ring-exchange interaction which serves as an elementary excitation for modelling unconventional topological matter. To reduce the thermal fluctuation in the Hubbard simulator, we cooled the lattice-trapped atoms with alternating superfluid reservoirs and realized a defect-free Mott insulators with a record-low entropy. When the simulator is scaled up to a 71-site one-dimensional chain, we realized the Coleman's phase transition and observed for the first-time gauge-invariance in quantum devises. Most recently, the achievement of a bosonic antiferromagnet represents a starting point for exploring exotic form of quantum magnetism with ultracold bosons.

报告人简介：

      Dr. Bing Yang received his B. S. from the Harbin Institute of Technology in 2009. He obtained his Ph.D. degree in physics from the University of Science and Technology of China in 2017. He participated a joint project in Heidelberg where he spends most of his Ph.D. (2012-2017) and the postdoctoral research (2017-2019). As the beginning of 2020, he becomes a senior post-doctoral fellow in the University of Innsbruck. Dr. Yang has dedicated many years to creating quantum entanglement and realizing exotic quantum matters with ultracold atoms in optical lattices. In this system, Dr. Yang and his team demonstrated for the first time the quantum spin entanglement (Nat. Phys., 2016), anyonic topological excitation (Nat. Phys. 2017) and quantum criticality of Tomonaga-Luttinger liquid (Phys. Rev. Lett. 2017). Recently, Dr. Yang and his team achieved a record-low temperature in the Hubbard simulator (Science 2020) and quantified its fundamental gauge invariance (Nature 2020).