  We propose a two-fluid description of fractional quantum Hall systems, in
which one component is a condensate of composite bosons and the other a Fermi
liquid formed by composite fermions (or simply electrons). We employ the theory
to model the interface between a fractional quantum Hall liquid and a
(composite) Fermi liquid metal, where we find a penetration of quantum Hall
condensate into the metallic region reminiscent of the proximity effect in
superconductor-metal interfaces. We also find a novel and physically reasonable
set of gapped quasielectron and neutral modes in fractional quantum Hall
liquids.
