Light propagation through an ensemble of ultracold Rydberg atoms in an electromagnetically-induced-transparency (EIT) configuration is studied. In strongly interacting Rydberg EIT media, nonlinear optical effects lead to a nontrivial dependence of the degree of probe-beam attenuation on the medium density and on its initial intensity. We develop a Monte Carlo rate equation model that self-consistently includes the effect of the probe-beam attenuation to investigate the steady state of the Rydberg medium driven by two laser fields. We compare our results to recent experimental data and to results of other state-of-the-art models for light propagation in Rydberg EIT media. We find that for low probe field intensities, our results match the experimental data best if a density-dependent dephasing rate is included in the model. At higher probe intensities, our model deviates from other theoretical approaches, because it predicts a spectral asymmetry together with line broadening. These are likely due to off-resonant excitation channels, which, however, have not been observed in recent experiments. Atomic motion and coupling to additional Rydberg levels are discussed as possible origins for these deviations.
We use the technique of electro-magnetically induced transparency (EIT) to probe the effect of attractive dipole-dipole interactions in a highly excited Rydberg gas. The transient character of the EIT response is investigated by rapidly scanning the probe laser through resonance. We characterize the resulting cooperative optical non-linearity as a function of probe strength, density and scan direction. For the 58D
5/2 Rydberg state, an atom density of $1.6\times10^{10}
cm^{-3}$ and a positive frequency scan we measure a third-order non-linearity of
χ(3)=5×10−7 m
2V
−2. For the reverse scan we observe a second order non-linearity of
χ(2)=5×10−6 mV
−1. The contrasting behaviour can be explained in terms of motional effects and resonant excitation of Rydberg pairs.
We use the technique of electro-magnetically induced transparency (EIT) to probe the effect of attractive dipole-dipole interactions in a hi ghly excited Rydberg gas. The transient character of the EIT response is investigated by rapidly scanning the probe laser through resonance. We characterize the resulting cooperative optical non-linearity as a function of probe strength, density and scan direction. For the 58D5/2 Rydberg state, an atom density of 1.6 � 10 10 cm 3 and a positive frequency scan we measure a third-order non-linearity of � (3) = 5 � 10 7 m 2 V 2 . For the reverse scan we observe a second order non-linearity of � (2) = 5 � 10 6 mV 1 . The contrasting behaviour can be explained in terms of motional effects and resonant excitation of Rydberg pairs.