  The incommensurate phase of a bilayer quantum Hall state is found to have a
``rippled'' dipole charge density whenever the layers are unbalanced. This
tunable dipole-density-wave instability could be detected by sensitive
capacitance measurements and by anisotropic transport. We demonstrate this
explicitly by carrying out a Hartree-Fock calculation of the layer densities
and capacitance for a double-layer quantum Hall state at a total filling factor
of 1.
