  Recent neutron scattering, nuclear magnetic resonance, and scanning tunneling
microscopy experiments have yielded valuable new information on the interplay
between charge and spin density wave order and superconductivity in the cuprate
superconductors, by using an applied perpendicular magnetic field to tune the
ground state properties. We compare the results of these experiments with the
predictions of a theory which assumed that the ordinary superconductor was
proximate to a quantum transition to a superconductor with co-existing
spin/charge density wave order.
