Electrically Control of Two-Dimensional Electron-Hole Fluids in the Quantum Hall Regime

We study the influence of perpendicular magnetic fields on the ground state of electron-hole bilayers separated by opaque tunnel barriers. In the absence of a field, the ground state at low carrier densities is a condensate of s-wave excitons that has spontaneous interlayer phase coherence. We find that a series of phase transitions emerge at strong perpendicular fields between condensed and incompressible incoherent states with full electron and hole Landau levels. When the electron and hole densities are unequal, condensation can occur in higher angular momentum exciton states. We explain how this physics is expressed in the two-dimensional gate-voltage phase diagrams of dual-gated bilayers.