Two-Color Optical Nonlinearity in an Ultracold Rydberg Atom Gas Mixture

Abstract

We report the experimental observation of strong two-color optical nonlinearity in an ultracold gas of 85 Rb-87 Rb atom mixture. By simultaneously coupling two probe transitions of 85 Rb and 87 Rb atoms to Rydberg states in electromagnetically induced transparency (EIT) configurations, we observe significant suppression of the transparency resonance for one probe field when the second probe field is detuned at ∼ 1 GHz and hitting the EIT resonance of the other isotope. Such a crossabsorption modulation to the beam propagation dynamics can be described by two coupled nonlinear wave equations we develope. We further demonstrate that the two-color optical nonlinearity can be tuned by varying the density ratio of different atomic isotopes, which highlights its potential for exploring strongly interacting multi-component fluids of light.