  In this work, we investigate the quantum phase transition in a non-Hermitian
XY spin chain. The phase diagram shows that the critical points of Ising phase
transition expand into a critical transition zone after introducing a
non-Hermitian effect. By analyzing the non-Hermitian gap and long range
correlation function, one can distinguish different phases by means of
different gap features and decay properties of correlation function, a tricky
problem in traditional XY model. Furthermore, the results reveal the
relationship among different regions of the phase diagram, non-Hermitian energy
gap and long range correlation function.
