Semiconductor quantum dots (QDs) are promising artificial atoms for quantum information processing: they can generate single photons flying quantum bits; they show single photon sensitivity promising to develop quantum gates and the spin of a carrier in a QD can be a quantum memory. The scalability of a quantum network requires efficient interfaces between stationary and flying quantum bits. In the last few years, our group has made important progresses in this direction using cavity quantum electrodynamics.
With a deterministic positioning of a single QD in a microcavity, we control the QD spontaneous emission on demand . With such technique highly efficient single photon sources with brightness as large as 80% are demonstrated . By minimizing the charge noise around the QD in a gated structure , we demonstrate the generation of fully indistinguishable photon. The source brightness is shown to exceed by one or two orders of magnitude the one of a parametric down-conversion source of same quality . Symmetrically, these devices perform as excellent interfaces between a flying quantum bit and a stationary one, where coherent control of a quantum bit can be done when only few photons .
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Characteristic low-threshold polariton lasing of organic and inorganic microcavity systems can only be achieved with
efficient population of the lower polariton ground state. In this regard, the key role undertaken by vibronic replicas and
molecular phonon it has been shown experimentally and theoretically predicted by various works. We report here, direct
observation of critical enhancement of polariton population density in strongly coupled J-aggregate based organic
microcavities. The process highlighted in our study is manifested by discrete maxima of the angular-resolved
photoluminescence intensity and interpreted by the mediation of molecular vibrations quanta characteristic of the active
material. By measuring the reduced time scale of vibrations driven relaxation dynamics, manifested by sub 100fs buildup
times, we emphasized the efficiency of the mechanism to overcome losses channel in disordered J-aggregate systems.
Hence, the realization of amplified polariton population with improved relaxation rates paves the way for the observation
of low threshold lasing, primary step for developing room temperature organic laser sources and ultra-fast optoelectronic
devices with less fabrication complexity than their crystalline counterparts.