  Long-lived indirect excitons (IXs) exhibit a rich phase diagram, including a
Bose-Einstein condensate (BEC), a Wigner crystal, and other exotic phases.
Recent experiments have hinted at a new, "classical" liquid of IXs above the
BEC transition. To uncover the nature of this phase, we use a broad range of
theoretical tools and find no evidence of a driving force towards classical
condensation. Instead, we attribute the condensed phase to a quantum
electron-hole liquid (EHL), first proposed by Keldysh for direct excitons.
Taking into account the association of free carriers into bound excitons, we
study the phase equilibrium between a gas of excitons, a gas of free carriers,
and an EHL for a wide range of electron-hole separations, temperatures,
densities, and mass ratios. Our results agree reasonably well with recent
measurements of GaAs/AlGaAs coupled quantum wells.
