Detecting degenerate bands topological invariants in optical lattice

Abstract

In this paper, we present a novel experimental approach for simulating and detecting topological invariants using ultracold fermions confined in two-dimensional hexagonal optical lattices. We propose achieving two-fold degenerate four-band models with non-trivial topologies in both the AII and A classes by introducing additional inertial forces, Raman processes, or periodic driving. By implementing various quench sequences and observing the evolution of the time-of-flight pattern, we can gather comprehensive information about the ground states and determine the topology of the valence bands. Through the analysis of tomographic results, we are able to extract and calculate the spin Chern number for both spin-conserving and spin-nonconserving cases. Additionally, we demonstrate the robustness of the quantized topological invariants and discuss the effects of various experimental parameters.