On an uncertainty principle for small index subgroups of finite fields

In this paper we continue the study of the nonvanishing minors property (NVM) initiated by Garcia, Karaali and Katz, for the compressed Fourier matrix attached to a subgroup $H$ of the multiplicative group of a finite field $\mathbb{F}_q$ and a character $χ$ defined over $H$. Here we provide a characterization of this aforementioned property for \textit{symmetries} arising from an index-3 subgroup $H$ and a nontrivial character $χ$.