Primitive Element Pairs with One Prescribed Trace over a Finite Field (1709.05540v2)

Abstract: In this article, we establish a sufficient condition for the existence of a primitive element $\alpha \in {\mathbb{F}{q^n}}$ such that the element $\alpha+\alpha^{-1}$ is also a primitive element of ${\mathbb{F}{q^n}},$ and $Tr_{\mathbb{F}{q^n}|\mathbb{F}{q}}(\alpha)=a$ for any prescribed $a \in \mathbb{F}q$, where $q=p^k$ for some prime $p$ and positive integer $k$. We prove that every finite field $\mathbb{F}{q^n}~ (n \geq5),$ contains such primitive elements except for finitely many values of $q$ and $n$. Indeed, by computation, we conclude that there are no actual exceptional pairs $(q,n)$ for $n\geq5.$