Exciton condensation, a collective phase-coherent state of bound electron-hole pairs, is expected to enable phenomena such as dissipationless counterflow and novel broken-symmetry states but has remained difficult to realize in zero magnetic field. In semiconductors, exciton condensation requires the exciton binding energy to exceed the band gap, where the binding energy derives from Coulomb attraction between electrons and holes. The absence of unambiguous observations indicates either that the binding energy is insufficient in most candidate systems or that, even if sufficient, the critical temperature is too low to permit clear experimental detection. To enhance the binding energy—and hence the critical temperature—we propose a different control parameter: an in-plane electric field. Being inversion odd, the electric field hybridizes low-lying excitons of opposite parity (e.g., $s$- and $p$-wave excitons), and one of the resulting hybrid modes is lower in energy via level repulsion. The in-plane electric field therefore enhances the effective binding energy, providing a different route to stabilizing exciton condensation. We illustrate the mechanism in biased bilayer graphene using a microscopic Bethe-Salpeter treatment and identify the resulting phase boundary for electric-field-induced condensation. We further compute properties of the electric-field-assisted condensate phase and identify several experimental signatures.

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• Excitons
• Landau-Zener effect
• Phase transitions
• Bilayer graphene
• Bose-Einstein condensates
• Superfluids
• Many-body techniques