Dr. Yanan Dai is an associate professor in the department of physics, Southern University of Science and Technology (SUSTech). He obtained his B.S. degree in space science and technology at Shandong University in 2013, and Ph.D degree in physics at the University of Pittsburgh in 2019. Before joining SUSTech in Aug. 2022, he worked as a postdoctoral research scientist in the department of chemistry at the Columbia University. His research interest is to probe exotic excited state dynamics in condensed matter materials, such as plasmonic spin topology and 2D polaron formation. By developing ultrafast interferometric time resolved photoemission electron microscopy (ITR-PEEM), he was the first to discover and image meron (half-skyrmion) like plasmonic spin textures that exist on the nanometer and femtosecond (nano-femto) spatiotemporal scales, which granted him the outstanding dissertation award from the international organization of Chinese physicists and astronomers. He is also an expert in developing extreme-UV probed time- and angle-resolved photoelectron spectroscopy (TR-ARPES), and achieved full-Brillouin zone detection of hot electron dynamics and electron-phonon couplings in 2D thermoelectric materials. His group at SUSTech will develop novel ultrafast optical and photoelectron spectromicroscopies to focus on the multi-dimensional probing of excited state dynamics, and further design structured light sources based on polarization passage on the Poincaré sphere, to perform vectorial Floquet engineering of quantum materials on the nano-femto scales, i.e. the Poincaré engineering.