SPMS Researchers Observe Critical Topological Phase Transition in Nature

Researchers from the School of Physical and Mathematical Sciences (SPMS) at NTU Singapore, led by Prof. Baile Zhang and Dr. Zheyu Cheng alongside Singapore and international collaborators, have proposed and experimentally demonstrated a new type of phase transition termed critical topological phase transition in a study published in Nature. 

Photo from: https://www.nature.com/articles/s41586-026-11067-5/figures/1 | Illustration of a periodically driven one-dimensional dimerized lattice model (the Floquet SSH α-chain) and its acoustic implementation.

Topology and criticality are both organizing principles of phase transitions, but they have long been considered incompatible. Topological phases require an energy gap to remain robust, whereas criticality occurs only when that gap closes completely. Using an acoustic metamaterial platform with engineered waveguide arrays, the NTU SPMS team and collaborators proved that topology can not only survive but also actively reorganize critical behavior directly within gapless regimes. They successfully detected topological Floquet edge states along critical boundaries and confirmed a topology-enforced multicritical point through entanglement-entropy measurements.

Read the full Nature paper here