In Hasan's group, Xu became an expert on Angle-Resolved Photoemission Spectroscopy (ARPES), a powerful tool to directly visualize the electronic band structures of materials. His research with Hasan on Weyl semimetals was named a Top-10 breakthrough of the year by PhysicsWorld.

Then, in 2016, Xu joined Professor Nuh Gedik's group at the Massachusetts Institute of Technology as a postdoctoral researcher. In Gedik's group and in close collaboration with Prof. Pablo Jarillo-Herrero, Xu obtained skills on optical/THz spectroscopy, electronic/optoelectronic transport and 2D material fabrication. His recent work has sparked great interest in studying nonlinear electronic responses in topological materials.

Xu has a broad interest in electronic and optical properties in quantum matters, with the particular emphasis on emergent quantum phenomena, such as topological and broken symmetry states. Combining the versatile tools that will be developed in the TopoXu LAB and powerful facilities provided by National Labs and worldwide beamlines, the Xu group will explore and uncover the stunning beauty of quantum crystals.