Quantum Optics Seminar by Andreas Reinhard – Niels Bohr Institute - University of Copenhagen

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Quantum Optics Seminar by Andreas Reinhard

Optical nonlinearities at the single-photon level are key ingredients for future photonic quantum technologies. Quantum dots embedded in photonic nano-cavities emerge as ideal candidates for the realization of such nonlinearities. The outline of my presentation is the realization of such a cavity QED system in the strong coupling regime using photonic crystals. The evidence for these ultra-strong nonlinearities is demonstrated by performing quantum correlation measurements of the light scattered off the system: When resonantly exciting a fundamental polariton transition, we observe antibunched light, demonstrating photon blockade. In contrast, the scattered photon stream is strongly bunched when we choose a laser frequency corresponding to a two-photon transition into the second Jaynes-Cummings manifold. In another experiment, we apply the single-photon nonlinearity for the demonstration of an ultrafast all-optical switch with switching times on the order of 20 picoseconds. In the end I will present first experimental results of a different approach to achieving single-photon nonlinearities – using a photonic dot consisting of a quantum well inside a fiber-cavity.
A. Reinhard, T. Volz et al., Strongly correlated photons on a chip, Nature Photonics 6, 93-96 (2012).

T. Volz, A. Reinhard et al., Ultrafast all-optical switching by single photons, arXiv:1111.2915(2011).