ABSTRACT
This chapter provides some background information about the discrete symmetries charge, space, and time and discusses how they are connected with the electric dipole moment (EDM) of an atomic system. This leads to a discussion of Schiff’s theorem and of mechanisms which allow an atom to have an EDM. The chapter describes the status of our own work on the YbF molecule and the prospects for using it to measure the electron EDM. It discusses the case of a nonrelativistic atom in which the nucleus has finite size and EDM, giving rise to a first-order energy shift in an external field through the volume effect. The chapter considers only the case of a spherical nucleus, and describes the experimental verification of the vector Aharonov-Casher phase. One discussion of suitable molecules is restricted to diatomics because the spectra for polyatomic systems are so much more complex.
