Name of the Principal Investigator (PI) : Jacek Kasprzak
Name of the PI’s host institution for the project : Institut Néel, CNRS, Grenoble, France
Full title : Propagative and Internal Coherence in Semiconductor Nanostructures
Short name : PICSEN
Duration in months : 60
This project concerns the field of coherent, nonlinear, ultrafast, light-matter interaction on a quantum level in solids. It will explore experimentally the limits of : i) the internal coherence of an individual light emitter ; ii) the radiative coupling between a pair of emitters. The individual emitters to be employed are excitons in semiconductors : either loosely bound to impurities or strongly confined in quantum dots. First, by embedding the emitters in photonic nanowires produced in Grenoble, collection of the coherent optical response of individual emitters will be amplified by nearly four orders of magnitude. This will provide unprecedented access to the emitters’ coherent interaction with phonons and their dephasing. The second objective is to demonstrate an efficient, controllable and non-local, coherent coupling mechanism between distant light emitters, which is a prerequisite for the construction of quantum logic gates and networks. Here, the aim is to demonstrate a radiative coupling — effectively a "wiring-up" of two emitters via a propagating electromagnetic field — using resonant quantum emitters embedded into in-plane one-dimensional waveguides, which permit virtually unattenuated propagation of coherence. The internal and propagative coherence of individual emitters and radiatively coupled pairs will be explored using methods of coherent nonlinear spectroscopy beyond the current state of the art. Specifically, in order to demonstrate radiative coupling, a heterodyne spectral interferometry technique with spatial resolution will be developed. For the remaining and the most challenging part of the project, this advanced spectroscopy technique will be combined with ultrafast pulse-shaping in order to perform long-range coherent manipulation within a pair of exciton-biexciton systems in two strongly-confining quantum dots. Achievement of this goal should enable performing logical operations between distant emitters, paving the way towards optical quantum information processing based on semiconductor technology.