Four-wave mixing in a non-degenerate four-level diamond configuration in the hyperfine Paschen-Back regime

Abstract: We present an experimental study of seeded four-wave mixing (4WM) using a diamond excitation scheme (with states from the 5S${1/2}$, 5P${1/2}$, 5P${3/2}$ and 5D${3/2}$ terms) in a thermal vapour of $^{87}$Rb atoms. We investigate the 4WM spectra under the application of a strong magnetic field (0.6 T). The Zeeman interaction is strong enough to realise the hyperfine Paschen-Back regime, which has the effect of separating the optical transitions by more than the Doppler width, thereby significantly simplifying the spectral features. We show that this facilitates a quantitative comparison, even in the regime of strong dressing, between experimental data and a simple theoretical model based only on four-level optical Bloch equations.