Title: Nonlinear Zeeman effect, line shapes and optical pumping in electromagnetically induced transparency,
Abstract: We perform Zeeman spectroscopy on a Rydberg electromagnetically induced
transparency (EIT) system in a room-temperature Cs vapor cell, in magnetic
fields up to 50~Gauss and for several polarization configurations. The magnetic
interactions of the $\vert 6S_{1/2}, F_g=4 \rangle$ ground, $\vert 6P_{3/2},
F_e=5 \rangle$ intermediate, and $\vert 33S_{1/2} \rangle$ Rydberg states that
form the ladder-type EIT system are in the linear Zeeman, quadratic Zeeman, and
the deep hyperfine Paschen-Back regimes, respectively. Starting in magnetic
fields of about 5~Gauss, the spectra develop an asymmetry that becomes
paramount in fields $\gtrsim40$~Gauss. We use a quantum Monte Carlo
wave-function approach to quantitatively model the spectra. Simulated spectra
are in good agreement with experimental data. The asymmetry in the spectra is,
in part, due to level shifts caused by the quadratic Zeeman effect, but it also
reflects the complicated interplay between optical pumping and EIT in the
magnetic field. Relevance to measurement applications is discussed. %The
simulations are also used to study optical pumping in the magnetic field and to
investigate the interplay between optical pumping and EIT, which reduces photon
scattering and optical pumping.