Condensed Matter Seminars
Krzysztof Gawedzki (ENS de Lyon)
112:028 (Nordita South)
Wednesday 13 September
15:30 - 16:30
I shall discuss a construction of Z_2-valued invariants of topological phases for 2d and 3d time-reversal symmetric crystals, both static and periodically driven. The construction uses a geometric structure (a gerbe) on U(N) that encodes ambiguities of the logarithm of a unitary matrix.