  When performed in the proper low field, low frequency limits, measurements of
the dynamics and the nonlinear susceptibility in the model Ising magnet in
transverse field, $\text{LiHo}_x\text{Y}_{1-x}\text{F}_4$, prove the existence
of a spin glass transition for $x$ = 0.167 and 0.198. The classical behavior
tracks for the two concentrations, but the behavior in the quantum regime at
large transverse fields differs because of the competing effects of quantum
entanglement and random fields.
