Quantum defects reveal links between symmetry and topology

Researchers are utilizing two-dimensional tensor network states to explore symmetry-enriched topological order, extending the framework to accommodate general symmetry actions. The work establishes a connection between graded matrix product operator algebras and the theory of graded unitary fusion categories, allowing for representations of topological defect superselection sectors. By analyzing dual phase transitions induced by gauging a global symmetry or condensing a bosonic subtheory, the team derived the relationship between resulting topological orders; this offers insight into how different quantum states connect. The interplay of symmetry and topology in entangled states of quantum matter produces physical phenomena such as the fractionalization of charge on anyonic quasiparticle excitations.…