Detecting quantum phase transitions in the Kitaev model through topological entanglement entropy.

We use exact diagonalization on up to 16 site clusters to investigate the isotropic point of the Kitaev honeycomb model under an applied magnetic field. Using the Kitaev-Preskill construction, we calculate the topological entanglement entropy (TEE), as a function of both the field strength and field orientation. We detect distinct anomalies in the TEE which are indicative of quantum phase transitions to and from the field induced gapped quantum spin liquid (QSL) phase, a new gapless intermediate QSL, and the higher field partially polarized phase. These results are corroborated by corresponding level crossings in the energy spectrum.