Chiral phase and quantum phase transitions of anisotropicXY chains with three-site interactions

Abstract

Chiral phase and quantum phase transitions of anisotropicXY chainswith the XZY − YZX type of three-site interaction are studied. The phase diagram is obtained by the study ofthe Lee–Yang zeros, order parameters, and ground-state energy. Besides the paramagneticand ferromagnetic phases, a new chiral phase is found after the introduction of three-siteinteractions. In the new phase, we find that the fidelity is zero and the von Neumann entropySL is proportionalto Alog2L with thecoefficient A≈1/3 the same as that in the anisotropy transition line ofXY chain without three-site interactions. From the ferromagnetic phase to theparamagnetic phase, the quantum critical behavior is same as that identified for theXY spin model without three-site interactions. In this critical line,SL is proportionalto Alog2L with A≈1/6, the same as that in the Ising transition line of theXY chain without three-site interactions. From the ferromagnetic phase to the chiral phase andfrom the chiral phase to the paramagnetic phase, the quantum phase transitions are similarto the anisotropy transitions.