  In this paper we assume quantum dots can be assimilated to Fermi Hubbard
sites when the Coulomb interaction between electrons is higher compared to
their tunneling. The study of pairwise entanglement in a small size array of
quantum dots allows to model each pair as a quadrit-quadrit system (4 $\times$
4 mixed state) instead of the more common and simplistic approach of describing
it in quantum information as a qubit-qubit system. We study the effect of
Coulomb interaction and temperature on pairwise entanglement as well as on
quantum coherence and total correlations. The crucial results of this study are
that entanglement resists better the increase in temperature when the Coulomb
interaction is stronger. Moreover, we successfully explain the behavior of
these correlations in terms of the energy spectrum, namely the ground state
degeneracy and the state energy difference.
