  According to perturbation theory predictions, QCD matter in the
zero-temperature, high-density limits of QCD at nonzero isospin chemical
potential is expected to be in a superfluid Bardeen-Cooper-Schrieffer (BCS)
phase of $u$ and $\bar{d}$ Cooper pairs. It is also expected, on symmetry
grounds, that such phase connects via an analytical crossover to the phase with
Bose-Einstein condensation (BEC) of charged pions at $\mu_\text{I}\geq
m_\pi/2$. With lattice results, showing some indications that the deconfinement
crossover also smoothly penetrates the BEC phase, the conjecture was made that
the former connects continuously to the BEC-BCS crossover. We compute the
spectrum of the Dirac operator, and use generalized Banks-Casher relations, to
test this conjecture and identify signatures of the superfluid BCS phase.
