  One of the conceptual tensions between quantum mechanics (QM) and general
relativity (GR) arises from the clash between the spatial nonseparability} of
entangled states in QM, and the complete spatial separability of all physical
systems in GR, i.e., between the nonlocality implied by the superposition
principle, and the locality implied by the equivalence principle. Possible
experimental consequences of this conceptual tension will be discussed for
macroscopically entangled, coherent quantum fluids, such as superconductors,
superfluids, atomic Bose-Einstein condensates, and quantum Hall fluids,
interacting with tidal and gravitational radiation fields. A minimal-coupling
rule, which arises from the electron spin coupled to curved spacetime, leads to
an interaction between electromagnetic (EM) and gravitational (GR) radiation
fields mediated by a quantum Hall fluid. This suggests the possibility of a
quantum transducer action, in which EM waves are convertible to GR waves, and
vice versa.
