Optics Seminar

On the quantum light-matter couplingin a semiconductor nanostructureJacek KasprzakInstitut Neel, CNRS, BP 166, F-38042 Grenoble Cedex 9, FranceMilestone achievements in cavity quantum electrodynamics (cQED) have just beenawarded with the Nobel prize in physics [1]. The underlying experiments were performedon individual atomic systems exploring light-matter interaction on a quantum level [2].cQED eects can now be observed also in solid state systems, which owing to their intrinsicstability are better suited for a scalable technology and commercialization. When a singlebosonic mode strongly couples to a single fermionic mode, a Jaynes-Cummings (JC) ladderis formed. This is realized here by combining photons conned in a micropillar cavity [3]with a single exciton (electron-hole pair bound by their electrostatic attraction), so as tocreate dressed states called polaritons.In this talk, I will present the measurements and modeling of the coherent anharmonicresponse of this strongly-coupled exciton-cavity system at resonance. Injecting two pho-tons into the cavity, we demonstrate ap2 larger polariton splitting with respect to thevacuum Rabi splitting [3]. This is achieved using coherent nonlinear spectroscopy, specif-ically four-wave mixing (FWM)[4], where the coherence between ground state and rst(second) rung of the JC ladder can be interrogated for positive (negative) delays betweenlaser pulses driving the FWM signal.As an outlook, I will highlight our recent spectroscopic studies of a multiexciton-cavity system, enabling pioneering investigations of its Tavis-Cummings physics [5] andthus paving the way towards long-range radiative coupling in a solid.[1] S. Haroche and D. J. Wineland[2] M. Brune et al Phys. Rev. Lett. 76 1800 (1996)[3] J. Kasprzak et al. Nature Mater. 9, 304 (2010).[4] W. Langbein and B.Patton Opt. Lett. 31, 1738 (2006)[5] F. Albert et al. Nature Comm. (2013)