  The Ultra Quantum Crystal (UQC) phases observed in quasi-one-dimensional
conductors of the Bechgaard salts family under magnetic field exhibit both Spin
Density Wave order and a Quantized Hall Effect, which may exhibit sign
reversals. We examine the case with no sign reversals. Collective modes in the
UQC have been shown to have a rich spectrum, with local Magneto-Roton like
minima. As the field increases, Magneto-Roton modes, which have minima at
quantized wave vectors, merge, or not, in the single particle excitation
continuum. In the high field phase, the Hall conductivity at zero temperature
is zero; at the transition from the N=1 phase, it has two Magneto-Roton modes,
the energies of which increase rapidly with magnetic field. The modes survive
until a critical field above which the high field phase looks more like a
perfect nesting insulating Spin Density Wave.

Condensed Matter