Hrvoje Petek, R. K. Mellon Professor in the Kenneth P. Dietrich School of Arts and Sciences’ Department of Physics and Astronomy is co-author of the article, "Plasmonic Topological Quasiparticle on the Nanometre And Femtosecond Scales," featured in the Dec. 23, 2020, issue of Nature.
In his research, Petek examined ideas surrounding the origins of light, taking snapshots of light, stopping light and using it to change properties of matter. He worked with collaborators Chen-Bin (Robin) Huang of the National Tsing Hua University in Taiwan and Atsushi Kubo of the Tsukuba University of Japan, as well as Dietrich School graduate student Yanan Dai on the experiments.
The team performed an ultrafast microscopy experiment where they trapped green light pulses as composite light-electron density fluctuation waves and imaged their propagation on a silver surface at the speed of light. These light waves came together from two sides to form a light vortex where light waves appeared to circulate about a stationary common core as a whirlwind of waves. The light vortex fields can potentially cause transitions in the quantum mechanical phase order in solid state materials, such that the transformed material structure and its mirror image cannot be superimposed, thus generating two materials that are topologically distinct.
Petek said such topological phase transitions are at the vanguard of physics research because they are thought to be responsible for some aspects of the structure of the universe. “Even the forces of nature, including light, are thought to have emerged as symmetry breaking transitions of a primordial field. Thus, the ability to record the optical fields and plasmonic vortices in the experiment opens the way to perform ultrafast microscopy studies of related light-initiated phase transitions in condensed matter materials at the laboratory scale,” he said.
Petek is a fellow of the American Association for the Advancement of Science, recipient of the 2019 Ahmed Zewail Award in Ultrafast Science and Technology, and winner of the University of Pittsburgh 2005 Chancellor's Distinguished Research Award.