Revealing divergent length scales in the Kitaev honeycomb model with quantum Fisher information

Quantum spin liquid (QSL) phases of matter have proven extremely elusive from both experimental and theoretical perspectives. In the theoretical domain, examining the topological entanglement entropy has been a primary tool for diagnosing whether or not a model exhibits QSL physics in its groundstate. We study the Kitaev honeycomb model, a prototype of QSL physics in two dimensions, using the quantum Fisher information (QFI), which is both experimentally accessible and well defined at finite temperature. We explore he behaviour of the QFI in both the gapped and gapless phases and in the regions around the transition.