  Searches for violations of the fundamental symmetries of parity P and time
reversal T in atomic and molecular systems provide a powerful tool for precise
measurements of the physics of and beyond the standard model. In this work, we
investigate how these symmetry violations affect the response of atoms and
molecules to applied electric and magnetic fields. We recover well-known
observables like the P-odd, T-odd spin-electric field coupling that is used for
searches of the electron electric dipole moment (eEDM) or the effect of P-odd,
T-even optical rotation in atomic gases. Besides these, we obtain several other
possible observables. This includes, in particular, effects that can only be
seen when using oscillating or inhomogeneous fields.
