Please circulate! Let us welcome Prof. Cenke Xu, in Live Action! Quantum Matter in Mathematics and Physics (QMMP) 2023: https://cmsa.fas.harvard.edu/event_category/quantum-matter-seminar/ ----- This seminar will be in person! *Time: Sept 28, Thur 4:30 pm - 6:00 pm ET * *Location: Harvard CMSA G10* Zoom: https://harvard.zoom.us/j/977347126 Password: cmsa ————————————————————————————————— Cenke Xu (UCSB) Title: Quantum field theory approach to quantum information Abstract: We apply the formalism of quantum field theory and Euclidean space-time path integral to investigate a class of quantum information problems. In particular, we investigate quantum many-body systems under weak-measurement and decoherence. The Euclidean space-time path integral allows us to map this problem to a quantum field theory with (temporal) boundary or defects. We therefore investigate two types of quantum many-body systems with nontrivial boundary physics: quantum critical points, and states with nontrivial topology, such as Chern insulator and symmetry protected topological states. For example, we demonstrate that a Wilson-Fisher quantum critical point can be driven into an "extraordinary-log" phase after weak-measurement. Another example is that, we argue that a system with higher form symmetry may be driven to a self-dual phase transition under weak-measurement. --- Harvard University CMSA, 20 Garden Street, Cambridge, MA 02138