Reentrant topology and reverse pumping in a quasiperiodic flux ladder

Abstract

Topological phases of matter are known to be unstable against strong onsite disorder in one dimension. In this work, however, we propose that in the case of a topological ladder, an onsite quasiperiodic disorder under proper conditions, first destroys the initial topological phase and subsequently, induces another topological phase through a gap-closing point. Remarkably, by allowing a staggered flux piercing through the plaquettes of the ladder, the gapless point bifurcates into two gapless critical lines, resulting in a trivial gapped phase sandwiched between the two topological phases. This results in a scenario where the system first undergoes a transition from one topological phase to a trivial phase and then to the other topological phase as a function of the quasiperiodic disorder strength. Such disorder induced re-entrant topological phase transition reveals a phenomenon of direction reversal in the topological transport, which we identify through Thouless charge pumping.