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

Chiral phase and quantum phase transitions of anisotropic XY chains with the XZY − YZX type of three-site interaction are studied. The phase diagram is obtained by the study of the Lee–Yang zeros, order parameters, and ground-state energy. Besides the paramagnetic and ferromagnetic phases, a new chiral phase is found after the introduction of three-site interactions. In the new phase, we find that the fidelity is zero and the von Neumann entropy SL is proportional to Alog2L with the coefficient A≈1/3 the same as that in the anisotropy transition line of XY chain without three-site interactions. From the ferromagnetic phase to the paramagnetic phase, the quantum critical behavior is same as that identified for the XY spin model without three-site interactions. In this critical line, SL is proportional to Alog2L with A≈1/6, the same as that in the Ising transition line of the XY chain without three-site interactions. From the ferromagnetic phase to the chiral phase and from the chiral phase to the paramagnetic phase, the quantum phase transitions are similar to the anisotropy transitions