Department of Physics, National University of Singapore

Upcoming Seminars

(Both online and in-person seminars will be broadcast via Zoom.)

(Click the upper right corner of this page to see the previous seminars and their recordings.)

The seminar series in the fall semester of 2025 is over, and the next seminar will take place in the spring semester of 2026.

Time: 9am, January 23 2026, GMT+8

Location: Online

Zoom: https://nus-sg.zoom.us/j/89156543585?pwd=wsrGn2Qs72kiMlqEb5zX7DDyWkcnP4.1

Password: 502120

Speaker: Vladimir Calvera

Title: Invariants for (2+1)D crystalline symmetry-protected topological phases 

Abstract: I will present a set of many-body invariants that characterize bosonic symmetry-protected (SPT) phases in two spatial dimensions with symmetry $G = G_{\text{space}}\times K$, where $G_{\text{space}}$ is a wallpaper group and K= U(1), Z_n or SO(3) is an internal symmetry. These invariants are obtained from expectation values of partial rotation and reflections, combined with internal symmetries. In particular, I will show that `partial rotations' and `partial double reflections’ are sufficient to distinguish crystalline SPTs on the square and triangular lattices. I will also discuss how these invariants relate to topological effective actions and quantum numbers of lattice defects.

This talk is based on arXiv:2510.26074 (with Naren Manjunath and Maissam Barkeshli).

Time: 9am, February 6 2026, GMT+8

Location: Online

Zoom: https://nus-sg.zoom.us/j/89156543585?pwd=wsrGn2Qs72kiMlqEb5zX7DDyWkcnP4.1

Password: 502120

Speaker: Richard Allen

Title: TBD

Abstract: TBD

There is no seminar during the week of February 16 2026 because of the Chinese Spring Festival.

There is no seminar during the week of February 23 2026 because it is the reading week at NUS.

There is no seminar during the week of March 30 2026 because of the Good Friday.