Onset of superfluidity in random media

The zero-temperature superfluid onset transition for a system of repulsively interacting bosons in a random potential is studied. The associated quantum critical behavior is characterized in d dimensions by exponents 2/d, and a dynamic exponent z. Static and dynamic scaling laws are derived: Some measureable exponents, such as z=d, are predicted exactly. Applications to experiments on He4 absorbed in porous media are discussed. © 1988 The American Physical Society.