  We investigate theoretically the fractional quantum Hall effect at
half-filling in the lowest Landau level observed in asymmetric wide quantum
wells. The asymmetry can be achieved by a potential bias applied between the
two sides of the well. Within exact-diagonalization calculations in the
spherical geometry, we find that the incompressible state is described in terms
of a two-component wave function. Its overlap with the ground state can be
optimized with the help of a rotation in the space of the pseudospin, which
mimics the lowest two electronic subbands.
