Proof of the absence of local conserved quantities in the spin-1 bilinear-biquadratic chain and its anisotropic extensions

Abstract: We provide a complete classification of the integrability and nonintegrability of the spin-1 bilinear-biquadratic model with a uniaxial anisotropic field, which includes the Heisenberg model and the Affleck-Kennedy-Lieb-Tasaki model. It is rigorously shown that all systems, except for the known integrable systems, are nonintegrable, meaning that they do not have nontrivial local conserved quantities. In particular, this result guarantees the nonintegrability of the Affleck-Kennedy-Lieb-Tasaki model, which is a fundamental assumption for quantum many-body scarring. Furthermore, we give simple necessary conditions for integrability in an extended model of the bilinear-biquadratic model with anisotropic interactions. Our result has accomplished a breakthrough in nonintegrability proofs by expanding their scope to spin-1 systems.