Focus on new faculty: Jun Xiao, shedding light on quantum materials

// Materials Science & Engineering

Photo of Jun Xiao

Jun Xiao

One of the frontiers in materials science and engineering research is quantum materials, including 2D layered materials which are ultrathin substances only one atom thick. When atoms are arranged in this manner, these materials often take on astounding properties, like unconventional superconductivity, special states of magnetism, ferroelectricity and increased light-matter interaction strength.

Jun Xiao, a new assistant professor in the Department of Materials Science and Engineering at the University of Wisconsin-Madison, aims to apply powerful, broadband ultrafast laser spectroscopy to both analyze and dynamically engineer 2D materials and other emerging quantum materials. The goal is to advance the fundamental material physics understanding and leverage their quantum properties for next-generation information and energy device applications.

Even though he is just starting his career, Xiao already has rich and high-level experience with lasers under his belt. His fascination began when he was a physics major at Nanjing University, where he began creating laser setups. He continued that work while completing his PhD at the University of California, Berkeley, in 2018 and most recently as a postdoctoral researcher at Stanford University and the SLAC National Accelerator Laboratory.

At UW-Madison, he hopes to continue his work with ultrafast lasers. “They are very powerful for highly non-equilibrium and nonlinear quantum phenomena,” he says. In his new lab, he will set up ultrafast laser systems covering a broad spectrum from ultraviolet to terahertz. “Light-matter interactions in terahertz regime nowadays are increasingly profound to understand and directly control many low-energy quantum information carriers in quantum solids, which can enable the advancement of quantum computing and 6G wireless communications. That’s the primary reason I want to develop such a new capability at UW-Madison.”

To study the properties of 2D materials like graphene or transition metal dichalcogenides, Xiao zaps the material with his laser, then uses a variety of linear and nonlinear optical spectroscopies to gather information like degrees of polarization, intensity, frequency and photon statistics. This allows him to infer certain properties of the materials. By tuning the same lasers, he can also change the 2D materials at the atomic level—inducing new electronic transitions and large lattice distortions. Those changes enable new quantum behaviors in the materials with the goal of producing functional properties useful for future computing, communications and sensing.

Xiao won’t be making these advances alone. He’s excited to work with a cluster of faculty members across UW-Madison who are investigating these promising quantum materials. “We have a bunch of great colleagues with expertise on material synthesis, characterization and modeling. Our techniques actually complement each other,” Xiao says. “So that will make us a joint force pushing into this area together.”

Xiao also likes the idea that the breadth of expertise at UW-Madison could help move materials he’s engineered or characterized to commercialization, which could have a direct impact on people’s lives. “Technology advancement is based on how we can invent and understand new types of materials,” he says. “I think materials science is a driving force for the whole society. That’s why I’m excited to join the MS&E department and make a contribution.”

Author: Jason Daley