  We investigate the effect of band-limited white Gaussian noise (BLWGN) on
electromagnetically induced transparency (EIT) and Autler-Townes (AT)
splitting, when performing atom-based continuous-wave (CW) radio-frequency (RF)
electric (E) field strength measurements with Rydberg atoms in an atomic vapor.
This EIT/AT-based E-field measurement approach is currently being investigated
by several groups around the world as a means to develop a new SI traceable RF
E-field measurement technique. For this to be a useful technique, it is
important to understand the influence of BLWGN. We perform EIT/AT based E-field
experiments with BLWGN centered on the RF transition frequency and for the
BLWGN blue-shifted and red-shifted relative to the RF transition frequency. The
EIT signal can be severely distorted for certain noise conditions (band-width,
center-frequency, and noise power), hence altering the ability to accurately
measure a CW RF E-field strength. We present a model to predict the changes in
the EIT signal in the presence of noise. This model includes AC Stark shifts
and on resonance transitions associated with the noise source. The results of
this model are compared to the experimental data and we find very good
agreement between the two.
