Spontaneous and explicit parity-time-symmetry breaking in drift-wave instabilities.

A method of parity-time- (PT) symmetry analysis is introduced to study the high-dimensional, complicated parameter space of drift-wave instabilities. We show that spontaneous PT-symmetry breaking leads to the ion temperature gradient instability of drift waves, and the collisional instability is the result of explicit PT-symmetry breaking. A new unstable drift wave induced by finite collisionality is identified.