Speaker： 安钧鸿 教授 兰州大学

  长期从事量子光学与量子信息研究，专注量子物理的基础问题。主持完成国家自然科学基金面上基金3项、国家自然科学基金专项基金与青年基金各1项；教育博士点基金和甘肃省自然科学基金各1项；中央军委科技委主题研究课题1项。在开放系统的量子调控领域的研究成果具有开创性，受到国内外同行的重视并部分地引领了相关研究的发展。多次组织和参加国内外大中型学术会议，并多次应邀在相关国际会议上作邀请报告。

  2013年入选教育部新世纪优秀人才支持计划；2016年入选甘肃省飞天学者；2017年入选中央军委科技委主题专家组专家；2018年入选中国物理学会量子光学专业委员会委员。2019年入选第四批国家“万人计划”青年拔尖人才。

Abstract：

Floquet engineering, i.e., coherent control via periodic driving, has become a highly versatile tool in quantum control. The main idea resides in that the concept of energy spectrum in static systems can be completely inherited as the quasienergy spectrum in periodically driven systems according to Floquet theory. Many efforts have been devoted to explore non-trivial effects induced by periodic driving on quantum systems. In this talk, I will report that interesting nonequilibrium quantum phase transitions (QPTs) can be triggered by engineering non-trivial band-gap structure and midgap bound state in the quasi-energy spectrum using periodic driving. I will clarify this idea by two examples. One is to induce exotic topological QPT in both of Hermitian and non-Hermitian systems by periodic driving. A widely tunable number of topologically protected edge modes can be generated by a well-designed periodic driving, which relaxes greatly the experimental realization in the static case. Another is to induce non-equilibrium QPT in the total system consisting of open system and its environment by periodic driving. It is found that whenever the QPT manifested by the formation of midgap states in the quasienergy spectrum occurs, the decoherence of the open system can be suppressed. This opens a door to control decoherence by periodic driving.

References：
[1] Qing-Jun Tong, Jun-Hong An, Jiangbin Gong, Hong-Gang Luo, and C. H. Oh, Generating Many Majorana Modes via Periodic Driving: A Superconductor Model, Phys. Rev. B 87, 201109(R) (2013).
[2] Chong Chen, Jun-Hong An, Hong-Gang Luo, C. P. Sun, and C. H. Oh, Floquet control of quantum dissipation in spin chains, Phys. Rev. A 91, 052122 (2015).
[3] Tian-Shi Xiong, Jiangbin Gong, and Jun-Hong An, Towards large-Chern-number topological phases by periodic driving, Phys. Rev. B 93, 184306 (2016).
[4] Chao Ma, Yuan-Sheng Wang, and Jun-Hong An, Floquet engineering of localized propagation of light in waveguide array, Phys. Rev. A 97, 023808 (2018).
[5] Hui Liu, Tian-Shi Xiong, Wei Zhang, and Jun-Hong An, Floquet engineering to exotic topological phases in cold-atom systems, Phys. Rev. A 100, 023622 (2019).
[6] Hong Wu and Jun-Hong An, Floquet Topological Phases of Non-Hermitian Systems, Phys. Rev. B 102, 041119(R) (2020).
[7] Si-Yuan Bai and Jun-Hong An, Floquet Engineering to Reactivate a Dissipative Quantum Battery, arXiv:2009.06982, to appear in Phys. Rev. A (R).

15:00， 2020-12-18

物理学院425