Gapless and Non-Equilibrium Topology in Blockaded Ladders

Abstract

We propose a multi-leg PXYP model as a minimal setting to explore constraint-induced intertwinement between itinerant and internal degrees of freedom. We argue that the Rydberg-like blockade induces correlations in squeezed space, providing a unified mechanism for nontrivial string order both in and out of equilibrium. In a two-leg geometry, this leads to an intrinsically gapless topological ground state, which can terminate at a supersymmetric multicritical point. This mechanism also leads to the preservation of string order for parametrically long times after a quench, which we verify using tensor network simulations and a classical stochastic approximation to the dynamics. In a three-leg geometry, the blockade leads to an additional emergent $U(1)$ symmetry, resulting in a multicomponent Luttinger liquid where both itinerant and internal degrees of freedom are critical. This family of models arises naturally in a range of quantum simulator platforms such as Rydberg tweezer arrays and dipolar atoms in optical lattices.

arXiv comment5+8 pages; 5 figures