Quantum Optics Seminar by Klemens Hammerer

Higher-order mean-field theory of light-atomic ensemble interactions

Light interacting with atomic ensembles is a paradigmatic example of an open many-body quantum system and, therefore, is generally not amenable to exact treatments. A frequently used method for approximate description is the mean-field approach, in which linearization is performed around large mean light amplitudes and atomic polarizations. At the example of an atomic ensemble weakly and chirally coupled to a one-dimensional wave-guide I will discuss the limitations of a mean-field treatment in comparision to its systematic extensions based on higher-order cumulant expansions. The differences between these models in terms of measurable variables such as power transmission, squeezing, and g2-correlation will be discussed. I will also indicate applications of a similar approach to Faraday-interaction of light with thermal atomic ensembles