  We present large-scale Monte-Carlo simulations of a two-dimensional (2d)
bilayer quantum Heisenberg antiferromagnet with random dimer dilution. In
contrast to the exotic scaling scenarios found in many other random quantum
systems, the quantum phase transition in this system is characterized by a
finite-disorder fixed point with power-law scaling. After accounting for strong
corrections to scaling, characterized by a leading irrelevant exponent of
\omega = 0.48, we find universal, i.e., disorder-independent, critical
exponents z=1.310(6) and \nu=1.16(3). We discuss the consequences of these
findings and suggest new experiments.
