  We show that non-abelian two-generator subgroups of right-angled Artin groups
are quasi-isometrically embedded free groups. This provides an alternate proof
of a theorem of A. Baudisch: that all two-generator subgroups are free or free
abelian. Additionally, it shows that they are quasi-isometrically embedded. Our
theorem also gives a method for detecting groups that are not isomorphic to a
subgroup of any RAAG. We present some counterexamples in subgroups with more
than two generators.
