Topological to magnetically ordered quantum phase transition in antiferromagnetic spin ladders with long-range interactions

We study a generalized quantum spin ladder with staggered long range interactions that decay as power-law exponent \alpha α . Using large scale Monte Carlo (QMC) and density matrix renormalization group (DMRG) simulations, we show this model undergoes transition from rung-dimer phase characterized by non-local string order parameter, to symmetry broken N'eel phase. find evidence the is second order. In magnetically ordered phase, spectrum exhibits gapless modes, while excitations in gapped are well described terms of triplons – bound states spinons across legs. obtain momentum resolved dynamic structure factor numerically defined triplon band evolves into magnon dispersion transition. further discuss possibility deconfined criticality model.