Speaker: 
Darrick Chang - ICFO

Title: 
The maximum refractive index of optical materials: from quantum optics to quantum chemistry

Abstract:
It is interesting to observe that all known optical materials have a refractive index that is of order unity at visible/telecom wavelengths. Furthermore, it is not easy to reconcile this with the fact that the individual atoms making up the material are well-known to have a huge optical response near resonance, when isolated, as characterized by a scattering cross section that is much larger than the physical size of the atom. Here, we discuss the role that non-perturbative collective effects and multiple scattering of light have on determining the index of a collection of atoms, starting from the “quantum optics” regime of well-isolated atoms, to the “quantum chemistry” regime relevant for real-life solids. We elucidate various mechanisms by which the index can be limited, either by pure electrodynamic effects or by many-body effects associated with quantum chemistry. We develop a minimal model suggesting that an ultrahigh index material (n~30) with low losses is in principle allowed by the laws of nature. If realizable, such a material would have profound implications for optical technologies, due to the extreme reduction of optical wavelength.

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QuCoLiMa Talks are the weekly seminar of the collaborative research center TRR 306 QuCoLiMa (Quantum Cooperativity of Light and Matter). The talks are given by (external) experts, whose research falls within the scope of QuCoLiMa.

More information at www.qucolima.de/talks