Key facts
- Critical topological states have been experimentally observed for the first time.
- The discovery challenges the requirement of an energy gap for topological properties.
- Researchers used entanglement entropy and spectra measurements to characterize the states.
- The phenomenon was observed in both one-dimensional and two-dimensional systems.
- The findings have potential applications in acoustic and optical devices.
Chinese physicists have experimentally observed critical topological states, a phenomenon previously thought impossible without an energy gap. This breakthrough, detailed in two papers published in Nature, bridges the fields of topological physics and critical phase transitions. Traditionally, physicists considered critical phenomena and topology as separate areas of study, with the latter requiring a 'gap' to maintain its properties. However, researchers led by teams from the University of Science and Technology of China and Nanyang Technological University, with key theoretical contributions from Ningbo Oriental Institute of Technology, have demonstrated that topological properties can exist even at critical points where the energy gap closes. They utilized novel methods to measure entanglement entropy and spectra, which are not constrained by the presence of a gap, to characterize these states in both one-dimensional and two-dimensional systems. This discovery challenges fundamental assumptions in physics and opens new avenues for research in quantum and statistical physics, with potential applications in acoustic and optical devices.