Assembling Kitaev honeycomb spin liquids from arrays of one-dimensional symmetry-protected topological phases

The Kitaev honeycomb model, which is exactly solvable by virtue of an extensive number of conserved quantities, supports a gapless quantum spin liquid phase as well as gapped descendants relevant for fault-tolerant quantum computation. We show that the anomalous edge modes of one-dimensional (1D) cluster-state-like symmetry-protected topological (SPT) phases provide natural building blocks for a variant of the Kitaev model that enjoys only a subextensive number of conserved quantities. The symmetry of our variant allows a single additional nearest-neighbor perturbation, corresponding to an anisotropic version of the Γ term studied in the context of Kitaev materials. We determine the phase diagram of the model using exact diagonalization. Additionally, we use the density matrix renormalization group to show that the underlying 1D SPT building blocks can emerge from a ladder Hamiltonian exhibiting only two-spin interactions supplemented by a Zeeman field. Our approach may provide a pathway toward realizing Kitaev honeycomb spin liquids in spin-orbit-coupled Mott insulators.