Criticality without frustration for quantum spin-1 chains

Understand

Frustration-free (FF) spin chains have a property that their ground state minimizes all individual terms in the chain Hamiltonian.

• We ask how entangled the ground state of a FF quantum spin-s chain with nearest-neighbor interactions can be for small values of s.
• While FF spin-1/2 chains are known to have unentangled ground states, the case s=1 remains less explored.
• We propose the first example of a FF translation-invariant spin-1 chain that has a unique highly entangled ground state and exhibits some signatures of a critical behavior.