PhD Defense by Immo Sollner – Niels Bohr Institute - University of Copenhagen

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PhD Defense by Immo Sollner

In this presentation we will focus on the study of quantum electrodynamics in photonic crystal waveguides.  We investigate the interplay between a single quantum dot and the fundamental mode of the photonic crystal waveguide. We demonstrate experimental coupling efficiencies for the spontaneous emission into the mode exceeding 98% for emitters spectrally close to the band-edge of the waveguide mode. In addition we illustrate the broadband nature of the underlying effects, by obtaining coupling efficiencies above 90% for quantum dots detuned from the band edge by as far as 20nm.  These values are in good agreement with numerical simulations.

Such a high coupling efficiency implies that the system can be considered an artificial 1D-atom, and we theoretically show that this system can generate strong photon-photon interaction, which is an essential functionality for deterministic optical quantum information processing.

We present the progress towards the experimental demonstration of a strong photon-photon nonlinearity in resonant transmission experiments and discuss some of the encountered difficulties.

In the final part of this presentation we discuss a novel type of photonic crystal waveguide and show its applications for on-chip quantum information processing. This structure was designed for the efficient mapping of two orthogonal circular dipole transitions to different propagation paths of the emitted photon, i.e. exhibits chiral quantum-dot-waveguide coupling.  Such a structure is ideally suited for a number of applications in quantum information processing and among others an on-chip spin-photon interface, a single photon transistor, and a deterministic cNOT gate.