  In this article, the atom excitation suppression is studied in two ways. The
first way of exploring the excitation suppression is by an external DC electric
field. The second way is to study the excitation suppression caused by electric
field generated by free charges, which are created by ionizing atoms. This
suppression is called Coulomb blockade. Here the Coulomb forces are created by
ions through ionizing atoms by a UV laser. The theory shows that the
interaction, which causes the suppression, is primarily caused by charge-dipole
interactions. Here the charge is the ion, and the dipole is an atom. In this
experiment, we use $^{85}$Rb atoms. The valence electron and the ion core are
the two poles of an electric dipole. The interaction potential energy between
the ion and the atom is proportional to $\frac{1}{R^2}$, and the frequency
shift caused by this interaction is proportional to $\frac{1}{R^4}$, where $R$
is the distance between the ion and the dipole considered. This research can be
used for quantum information storage, remote control, creating hot plasmas
using cold atoms, as well as electronic devices.
