Quantum Matter Seminar

The concepts of symmetry-protected topological (SPT) phases and quantum anomaly can be generalized to mixed quantum states. In this talk I will give an overview of recent progress on this direction and highlight a few results. Specifically, I will discuss (1) a definition of SPT phases in mixed quantum states; (2) a scheme to characterize and classify mixed state SPT using defect decoration; (3) simple examples of "intrinsically mixed" SPT phases that have no pure state analogue; and (4) consequences of quantum anomaly on SPT boundary — specifically, constraints on quantum entanglement structure in terms of multi-partite separability.