  A permanent electric dipole moment (EDM) of a physical system requires
time-reversal (T) and parity (P) violation. Experimental programs are currently
pushing the limits on EDMs in atoms, nuclei, and the neutron to regimes of
fundamental theoretical interest. Here we calculate the magnitude of the
PT-violating EDM of 3He and the expected sensitivity of such a measurement to
the underlying PT-violating interactions. Assuming that the coupling constants
are of comparable magnitude for pi-, rho-, and omega-exchanges, we find that
the pion-exchange contribution dominates. Our results suggest that a
measurement of the 3He EDM is complementary to the planned neutron and deuteron
experiments, and could provide a powerful constraint for the theoretical models
of the pion-nucleon PT-violating interaction.
