  We discuss a model wherein soft gamma-ray repeaters (SGRs), anomalous X-ray
pulsars (AXPs), and radio quiet isolated neutron stars (RQINSs) are all compact
objects exhibiting superconductivity, namely color-flavor locked quark stars.
In particular we calculate the magnetic field decay due to the expulsion of
spin-induced vortices from the star's superfluid-superconducting interior, and
the resultant spin-down rate. We find that, for initial parameters
characteristic of AXPs/SGRs ($10^{13}<B<10^{14}~\rm{G}$; $3<P<12~\rm{s}$), the
magnetic field strengths and periods remain unchanged within a factor of two
for timescales of the order of $5\times 10^{5} - 5\times 10^{7}~\rm{yrs}$ given
a quark star of radius $10~\rm{km}$. Within these timescales, we show that the
observed period clustering in RQINSs can be explained by compactness, as well
as calculate how the magnetic field and period evolve in a manner concurrent
with RQINS observations.
