Robust approach to study the effect on quantum phase transitions of various perturbations at finite temperatures

Abstract

We propose using maximum coherence (${\mathrm{QC}}_{\mathrm{max}}$) to study quantum phase transition (QPT). We investigate several well-known models, such as the XXZ model, ${J}_{1}\text{\ensuremath{-}}{J}_{2}$ model, and one-dimensional spin Kitaev model. The results show that ${\mathrm{QC}}_{\mathrm{max}}$ can be used to detect different types of QPTs, including the Berezinskii-Kosterlitz-Thouless and topological types. In addition, ${\mathrm{QC}}_{\mathrm{max}}$ is more robust against interferences, such as thermal fluctuations and measurement interferences, than any existing detector. This property enables ${\mathrm{QC}}_{\mathrm{max}}$ to identify QPTs in experiments, where temperature effects and measurement interferences always exist. Thus, ${\mathrm{QC}}_{\mathrm{max}}$ might be an ideal tool for studying QPTs because of its measurability, universality, and robustness against interferences.