Winding number as topological invariant in Su-Schrieffer-Heeger (SSH) model

Question

I'm studying the SSH model, here's the reference. I don't get what the definition of a topological invariant is in this case. I think the important property is that the winding number cannot be changed without either breaking a symmetry of the system or closing the bulk band gap, but why do we call it a topological invariant?

fbs147 · Answer

To some extent, the time-reversal symmetry and the inversion symmetry protect the topological phase. This phenomenon is called symmetry protected topological phases--SPT. So when winding number is equal to 1(0), it is a topological(trivial) phase. The two regimes can not be smoothly connected by continuously deforming the mapping without closing the gap.

Answered by fbs147 on October 4, 2021

Winding number as topological invariant in Su-Schrieffer-Heeger (SSH) model

One Answer

Add your own answers!

Ask a Question