  We review the physics of atoms and clocks in weakly curved spacetime, and how
each may be used to test the Einstein Equivalence Principle (EEP) in the
context of the minimal Standard Model Extension (mSME). We find that
conventional clocks and matter-wave interferometers are sensitive to the same
kinds of EEP-violating physics. We show that the analogy between matter-waves
and clocks remains true for systems beyond the semiclassical limit. We
quantitatively compare the experimentally observable signals for EEP violation
in matter-wave experiments. We find that comparisons of $^{6}$Li and $^{7}$Li
are particularly sensitive to such anomalies. Tests involving unstable
isotopes, for which matter-wave interferometers are well suited, may further
improve the sensitivity of EEP tests.
