# Online Seminar: Jeongwan Haah (Microsoft), Topological phases of discrete time evolution #### calendar\_today Date and Time **June 15, 2021** 10:00AM - 10:00AM EDT #### pin\_drop Location **Zoom** ![Jeongwan Haah](/sites/g/files/omnuum6611/files/styles/hwp_1_1__720x720_scale/public/mathpicture/files/jeongwan_haah_photo.jpeg?itok=QaYVxYtD) **Location:** Zoom **Time:** Tuesday, 10:00 AM (Eastern US), 15:00 (UK/Eire), 16:00 (Central Europe), 22:00 (China) **Title:** Topological phases of discrete time evolution **Abstract:** In the Heisenberg picture of quantum mechanics, time evolution is a one-parameter family of automorphisms of operator algebra. Restricted to short times, the equivalence between time evolution and quantum circuits, especially the property that it maps a local operator to another, has been implanted in theoretical studies of topological phases of matter. In this talk, I will explain recent findings that not all locality-preserving automorphisms, also called quantum cellular automata, can be written as quantum circuits—there exists a “discrete time dynamics” that cannot have a “Hamiltonian.” These are tightly related to static, topological many-body states. I will give results on the classification of these automorphisms and connect them to locally generated subalgebras in one lower dimension. **Additional Ways to Join** Join by telephone (use any number to dial in) +1 929 436 2866 +1 312 626 6799 +1 669 900 6833 400 669 9381 China Toll-free International numbers available: [https://harvar](https://harvard.zoom.us/u/aclg6kOggb)[d.zoom.us/u/aclg6kOggb](https://harvard.zoom.us/u/aclg6kOggb) One tap mobile: +19294362866,,779283357# US (New York) Join by SIP conference room system Meeting ID: 779 283 357 <779283357@zoomcrc.com> Share on:- [ Facebook ](#) - [ Twitter ](#) - [ Linkedin ](#) Save: [ Add to calendar calendar\_today ](https://mathpicture.fas.harvard.edu/node/1590346/event-feed.ics) Copy link link