QED with a parabolic mirror

01.01.2014, 00:00

Newsletter 7

The physics of strong light-matter coupling has attracted much attention over the last few years. Since the early nineteen eighties, single atoms have been coupled to optical cavities, leading to fundamental demonstrations of cavity quantum electro-dynamics (QED) in which the atom can excite only one or a few radiation modes. The opposite regime of free-space QED, where a continuum of modes is available, has recently also received notable recognition.  In this case it is essential to increase the strength of the light-matter interaction:  focusing light, matching the incoming field with the spatial and temporal atomic radiation mode, and tailoring the polarization pattern can improve the coupling to a nearly perfect value. An intriguing intermediate situation between the single-mode and the continuum limit is the case of a large cavity, in which an atom couples to a large but not continuous number of modes.  A parabolic cavity is a remarkable example of this, ensuring that light entering parallel to the axis couples to an atom located at its focus in a particularly efficient way. In this paper, we look into the QED of a two-level atom located at the focus of a parabolic mirror. We find the vector field modes that can couple efficiently to the atom (a density plot is sketched in the figure). In terms of them, we study the ensuing modifications of the spontaneous emission, as well as the quantum statistical properties of the generated photon. 

Contact: gernot.alber(at)mpl.mpg(dot)de
Group: Leuchs Division
Reference: G. Alber et al., Phys. Rev. A 88, 023825  (2013). [selected as Editor's suggestion]