Dynamical solitons and boson fractionalization in cold-atom topological insulators

Abstract

We study the ${\mathbb{Z}}_2$ Bose-Hubbard model at incommensurate densities, which describes a one-dimensional system of interacting bosons whose tunneling is dressed by a dynamical ${\mathbb{Z}}_2$ field. At commensurate densities, the model is known to host intertwined topological phases, where long-range order coexists with non-trivial topological properties. This interplay between spontaneous symmetry breaking (SSB) and topological symmetry protection gives rise to interesting fractional topological phenomena when the system is doped to certain incommensurate fillings. In particular, we hereby show how topological defects in the ${\mathbb{Z}}_2$ field can appear in the ground state, connecting different SSB sectors. These defects are dynamical and can travel through the lattice carrying both a topological charge and a fractional particle number. In the hardcore limit, this phenomenon can be understood through a bulk-defect correspondence. Using a pumping argument, we show that it survives also for finite interactions, demonstrating how boson fractionalization can occur in strongly-correlated bosonic systems, the main ingredients of which have already been realized in cold-atom experiments.

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Cited by in corpus (14)

• Bulk-boundary-defect correspondence at disclinations in rotation-symmetric topological insulators and superconductors
• Recent progress on quantum simulations of non-standard Bose-Hubbard models
• ${\mathbb{Z}}_n$ solitons in intertwined topological phases
• Nonlinear Thouless Pumping of Solitons Across an Impurity
• Dynamical gauge fields with bosonic codes
• Transport of Vector Solitons in Spin-Dependent Nonlinear Thouless Pumps
• Cold atoms meet lattice gauge theory
• Topological bosonic Bogoliubov excitations with sublattice symmetry
• Revealing the topological nature of the bond order wave in a strongly correlated quantum system
• Tuning long-range fermion-mediated interactions in cold-atom quantum simulators
• Non-resonant inter-species interaction and its effect on the position response function of cold atoms
• Devil's staircase of topological Peierls insulators and Peierls supersolids
• Higher-order topological quantum paramagnets
• Bosonic Peierls state emerging from the one-dimensional Ising-Kondo interaction