Acoustic experiments confirm topology can persist at gapless critical points

https://phys.org/news/2026-10-acoustic-topology-persist-gapless-critical.html

"topological edge state was believed to rely on protective energy gap to survive... but now found to endure when energy gap completely closes, demonstrated using acoustic metamaterial platforms... expands beyond conventional bandgap systems into quantum critical regimes... furthers design of resilient, fault-tolerant, acoustic/ photonic metamaterial wave-guiding devices, technologies involving nonequilibrium topological phases of matter... topological quantum computation"