  Magnetic impurities embedded in inert solids can exhibit long coherence times
and interact with one another via their intrinsic anisotropic dipolar
interaction. We argue that, as a consequence of these properties, disordered
ensembles of magnetic impurities provide an effective platform for realizing a
controllable, tunable version of the dipolar quantum spin glass seen in
LiHo$_x$Y$_{1-x}$F$_4$. Specifically, we propose and analyze a system composed
of dysprosium atoms embedded in solid helium. We describe the phase diagram of
the system and discuss the realizability and detectability of the quantum spin
glass and antiglass phases.
