Topologically protected two-fluid edge states

Abstract

Edge states reveal the nontrivial topology of energy band in the bulk. As localized states at boundaries, many-body edge states may obey a special symmetry that is broken in the bulk. When local particle-particle interaction is induced, they may support a particular property. We consider an extended two-dimensional Su-Schrieffer-Heeger Hubbard model and examine the appearance of $\eta$-pairing states, which are excited eigenstates related to superconductivity. In the absence of Hubbard interaction, the energy band is characterized by topologically invariant polarization in association with edge states. In the presence of on-site Hubbard interaction, $\eta$-pairing edge states appear in the topologically nontrivial phase, resulting in the condensation of pairs at the boundary. In addition, as Hamiltonian eigenstates, the edge states contain paired fermions and unpaired fermions. Neither affects the other; they act as two-fluid states. From numerical simulations of many-body scattering processes, a clear manifestation and experimental detection scheme of topologically protected two-fluid edge states are provided.

11 pages, 9 figures

References in corpus (6)

• The physics of exceptional points
• Novel Topological Phase with Zero Berry Curvature
• Metastable superfluidity of repulsive fermionic atoms in optical lattices
• Heating-Induced Long-Range $\eta$-Pairing in the Hubbard Model
• Symmetry-Protected Scattering in Non-Hermitian Linear Systems
• Sudden death of particle-pair Bloch oscillation and unidirectional propagation in a one-dimensional driven optical lattice

Cited by in corpus (1)

• $\eta$-pairing states in the Hubbard model with non-uniform Hubbard interaction