SSH Model
The SSH chain alternates hopping amplitudes t₁ (intracell) and t₂ (intercell). When t₂ > t₁, the chain is in a topologically non-trivial phase with winding number W=1, hosting zero-energy edge states protected by chiral symmetry. When t₁ > t₂, W=0 and no edge states exist.
Controls
Key Physics
• Bulk gap: Δ = 2|t₁ − t₂|
• Winding number W = ½·sgn(t₂ − t₁) ∈ {0,1}
• Bulk-boundary correspondence: W edge modes per boundary
• Edge states are topologically protected (robust to disorder)