Carnegie Mellon University
October 17, 2022

Theoretical Physicist Vlad Kozii Joins CMU

By Heidi Opdyke

Jocelyn Duffy
  • Associate Dean for Communications, MCS
  • 412-268-9982

In the Mellon College of Science's Department of Physics, theoretical physicists seek to address some of the most challenging open problems in particle physics, condensed matter physics, biological physics, gravitation and cosmology.

Vlad Kozii, a new assistant professor of physics with a background in condensed matter physics, studies topological materials and their novel properties.

"In my work, I aim to address both questions of fundamental importance and those having a clear connection to existing or ongoing experiments; many of my works were inspired by or eventually related to certain experimental findings," said Kozii, who joined CMU recently. "Physics is a science about our nature and how our nature works."

CMU was the right place for Kozii in part because of the brilliant faculty members in the Department of Physics, he said. Along with the University of Pittsburgh nearby and a strong student base at both institutions, coming to Pittsburgh made his choice easy, he added.

"As a theoretical physicist, part of my job is to predict something new or understand and interpret what experimentalists are finding," he said.

Previously Kozii was a postdoctoral associate in Materials Sciences Division at the Lawrence Berkeley National Laboratory and the Department of Physics at the University of California, Berkeley.

Working in the group of Professor Joel Moore and collaborating with the lab of Professor Dan Stamper-Kurn, Kozii co-authored on a recent paper in the journal Science titled "Direct geometric probe of singularities in band structure."

"What we found was interesting and exciting," Kozii said. "That paper is in the area of atomic physics. While I am primarily a condensed matter physicist, these two areas overlap significantly these days."

One way these areas overlap is investigating the concept of topology in physics, which is the mathematical study of geometric properties preserved through smooth deformations of an object.

Physicists realized that this originally abstract concept could be applied to solid state physics and could have applications to a broad class of systems. Atomic physicists, on the other hand, found out that carefully positioned lasers can create electromagnetic fields such that the atoms within those fields mimic topological condensed matter systems.

"It's a very different set up and physical system, but the equations that describe the atomic motion are the same as the equations of motion for electrons in solids," Kozii said.

The team at Berkeley studied topological properties of ultracold rubidium atoms placed in a laser-created potential that mimics a two-dimensional honeycomb crystal lattice. The experimentalists involved developed new methods to study topological points where multiple energy surfaces are degenerate (intersect) and that exhibit singular geometry of the wave functions, which affects the properties of the material in a very nontrivial way.

"My work was to provide a theoretical explanation and interpret the experimental data. In particular, the task was to reveal and prove the topological nature of the features observed in the experimental setup and relate them to other interesting theoretical concepts," he said.

Kozii earned his doctoral degree from the Massachusetts Institute of Technology. He previously earned his master's and bachelor's degrees from the Moscow Institute of Physics and Technology.