Mode Splitting Of A Cavity With Birefringence Rubidium Vapor

The unique modes of the optical field distributing in a cavity give the research of interaction of intracavity light and atoms special importance. From the view of quantum electrodynamics, the strong coupling between the cavity and atoms makes the two parts into a whole one, so they would share one set of energy levels which are different from those of sole cavity or atoms, then the peak(s) of the transmission of the vacuum cavity will be split when atoms are inserted into it. As a compare, the semiclassical or classical approach account such splitting as the tiny change in the susceptibility of the atomic ensemble which is enhanced by the cavity and displayed in the transmission spectrum. The application of cavity in the study of interaction between light and atoms makes this long been extensively researched subject to generate new ideas. It is usually required that the cavity and atomic medium are strongly coupled in relevant study. For example, by the strong coupling between cavity and atomic medium, the entanglement between photons or atoms can be established, which would provide a media for the transmission of quantum information.The normal mode splitting appears in cavity’s transmission spectrum under the strong coupling regime. Research on the normal mode splitting can deepen our understanding of the interaction between light and atoms. To get the strong coupling between cavity and single atom, it is usually required to improve cavity’s finesse and reduce its mode volume. Such requirement means very complicated technology in practice. However it is much easier to get strong coupling between cavity and multi-atoms. This article shows our research of the normal mode splitting and multi normal mode splitting in the strong coupling regime of cavity and atomic medium.First, we simply review the related cavity quantum electrodynamics background of normal mode splitting, and introduce some typical experimental research with atomic beam, cold atoms, BEC, and hot atoms. The treatment methods as well as the novelties of these experiments can provide a good reference for our experiments.Secondly we give detailed analysis and calculation of the dispersion properties of two-level atom medium, and obtain the transmission spectra formula of the cavity and cold atoms (or atomic beam) medium system. The effects of Doppler broadening on the dispersive properties of the medium and the transmission spectrum formula have also been further analyzed.Then we introduce the experimental setup and procedure, and analyze experimental data. The normal mode splitting and multi normal mode splitting have been seen under strong (or even superstrong) coupling condition in our experiment.Finally, the effect of magnetic field on the dispersion properties of the medium has been theoretically and experimentally studied. The normal mode splitting and multi normal mode splitting of non-degenerate two-level atomic medium is shown. Its potential application in measuring weak magnetic field is discussed.