Many-body generalization of the Z2 topological invariant for the quantum spin Hall effect.
We propose a many-body generalization of the Z2 topological invariant for the quantum spin Hall insulator, which does not rely on single-particle band structures. The invariant is derived as a topological obstruction that distinguishes topologically distinct many-body ground states on a torus. It is also expressed as a Wilson loop of the SU(2) Berry gauge field, which is quantized due to time-reversal symmetry.
Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106, USA.
Sung-Sik
SS
Lee
Shinsei
S
Ryu