  We prove that the addition of an arbitrarily small random perturbation of a
suitable type to a quantum spin system rounds a first order phase transition in
the conjugate order parameter in d <= 2 dimensions, or in systems with
continuous symmetry in d <= 4. This establishes rigorously for quantum systems
the existence of the Imry-Ma phenomenon, which for classical systems was proven
by Aizenman and Wehr.
