Title: Hidden order and symmetry protected topological states in quantum link ladders,
Abstract: We show that whereas spin-1/2 one-dimensional U(1) quantum-link models (QLMs)
are topologically trivial, when implemented in ladder-like lattices these
models may present an intriguing ground-state phase diagram, which includes a
symmetry protected topological (SPT) phase that may be readily revealed by
analyzing long-range string spin correlations along the ladder legs. We propose
a simple scheme for the realization of spin-1/2 U(1) QLMs based on
single-component fermions loaded in an optical lattice with s- and p-bands,
showing that the SPT phase may be experimentally realized by adiabatic
preparation.