The authors study in depth the Rohlin property for quasi-free automorphisms \(\alpha\) of the fermion algebra \(A\) and give several characterizations of the property. For instance, it is shown that the property is equivalent to the following conditions:
(1) \(\alpha^n\) is weakly outer in the trace representation for all nonzero integers \(n\).
(2) the crossed product \(A\rtimes_\alpha\mathbb{Z}\) has a unique trace;
(3) \(A\rtimes_\alpha\mathbb{Z}\) has real rank zero.
Some facts about equi-distribution of points on the unit circle are needed in the arguments.