Quantum Hall bilayer in dipole representation

Abstract

The quantum Hall bilayer (QHB) at filling factor $ \nu = 1 $ represents a competition between Bose-Einstein condensation (BEC) at small distances between layers and fermionic condensation, whose influence grows with distance and results in two separate Fermi liquid states for the underlying quasiparticles at very large (or infinite) distances. The question that can be raised is whether, at intermediate distances between layers, a distinct phase exists, or if a singular transition occurs, with the possibility that this happens at infinite distances. Here, using a dipole representation for fermionic quasiparticles, we find support for the latter scenario: Within a large and relevant range of distances, BEC condensation, identified as Cooper $ s $-wave pairing of dipole quasiparticles, prevails over both Cooper $ p $-wave pairing and $ s $-wave excitonic pairing of the same quasiparticles.