Periodic driving has become one useful and versatile tool in quantum engineering. In this talk, I will report that interesting nonequilibrium topological phase transitions (QPTs) can be synthesized by engineering the formation of midgap bound state in Floquet quasienergy spectrum using periodic driving. I will clarify this idea by two examples. One example is to induce more colorful topological QPT in one-dimensional Kitaev model.  A tunable number of topologically protected Majorana modes are generated in Kitaev model by a well-designed periodic driving, which may supply a novel way to identify the formation of the Majorana modes in the system. The other example is to induce large-Chern-number topological insulator phases in two-dimensional two-band model. The topological insulator phases with large and widely tunable Chern numbers can be triggered by periodic driving, which is exemplified in Haldane model. Our approach may lift experimental difficulties in material fabrication to realize the large-Chern-number topological phases.

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] Tian-Shi Xiong, Jianbing Gong, and Jun-Hong An, Towards large-Chern-number topological phases by periodic driving, Phys. Rev. B 93, 184306 (2016).

Prof. An Jun-Hong received his Ph. D. in Physics from Lanzhou University in 2005 and then joined Lanzhou University. From 2006 to 2007, he performed postdoctoral research in National Cheng-Kung University. From 2007 to 2008 and 2009 to 2010, he worked in National University of Singapore as a research fellow. From 2011 to 2014, he was appointed as a visiting research fellow in National University of Singapore. Prof. An's recent research work involves decoherence of open quantum systems and its control, quantum and topological phase transitions induced by periodic driving.