Topological invariants for Floquet-Bloch systems with chiral, time-reversal, or particle-hole symmetry

Article

关键词: QUANTUM-WELLS;    INSULATORS;   

DOI  :  10.1103/PhysRevB.97.045140

来源: SCIE

【 摘 要 】

We introduce Z(2)-valued bulk invariants for symmetry-protected topological phases in 2 + 1-dimensional driven quantum systems. These invariants adapt the W-3 invariant, expressed as a sum over degeneracy points of the propagator, to the respective symmetry class of the Floquet-Bloch Hamiltonian. The bulk-boundary correspondence that holds for each invariant relates a nonzero value of the bulk invariant to the existence of symmetry-protected topological boundary states. To demonstrate this correspondence we apply our invariants to a chiral Harper, time-reversal Kane-Mele, and particle-hole symmetric graphene model with periodic driving, where they successfully predict the appearance of boundary states that exist despite the trivial topological character of the Floquet bands. Especially for particle-hole symmetry, the combination of the W-3 and the Z(2) invariants allows us to distinguish between weak and strong topological phases.

【 授权许可】

Free