Let $E$ be a separable Banach space and let $T\in L(E,E)$. Is there a condition on $T$ ensuring that: $$ \mbox{$\{x_n\}_{n=1}^N\subseteq E$ is linearly independent} \Rightarrow \{T(x_n)\}_{n=1}^N\cup \{x_n\}_{n=1}^N \mbox{ is a independent in $E$}? $$ Is $T$ [mixing][1] enough for this? Are such objects studied in the literature? [1]: https://en.wikipedia.org/wiki/Mixing_(mathematics)