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Quantum information processing with semiconductor quantum dots

Vendredi 2 décembre 2016 10:30 - Duree : 1 heure
Lieu : LNCMI, salle de conférences "René Pauthenet" (bâtiment J, 2ème étage) - 25 rue des martyrs - 38000 Grenoble

Orateur : Olivier GAZZANO (National Institute of Standards and Technology & University of Maryland, USA)

Semiconductor quantum dots are increasingly seen as promising light sources for quantum information processing. Through a series of important improvements, th ese sources can be used in various quantum information processing experiments (review article [1]). In this talk, I will highlight this process and present my contribution to the field. I will first discuss the optimization of key parameters of the quantum dot light sources. We insert single InAs quantum dots in pillar microcavities to benefit from cavity quantum electrodynamic effects (Fig. a). We obtain large single-photon purity and indistinguishability of the emitted photons, combined with high emission brightness [2]. Unlike more pristine systems, quantum dots are inherently coupled to their solid-state environment, creating rich physics. We perform resonant fluorescence spectroscopy and we observe the inhomogeneous broadening of QD states induced by electromagnetic fluctuations in the QD vicinity. We observe an enhancement of the QD properties using a weak above band laser : the source gets brighter and the inhomogeneous linewidth becomes narrower (Fig. b). From this, we develop a qualitative picture of the solidstate environmental effects on the QD [3]. These bright sources of quantum light can already be used in quantum optics and quantum information experiments. We implement a quantum Controlled-NOT gate using quantum dot photons and we use it to generate two-photon entangled states with a large fidelity to a Bell state [4]. We also developed a 4 detectors scheme to simultaneous determine the purity and indistinguishability of single photon characterizations that up to now require multiple, sequential measurements [5].

[1] O. Gazzano and G. S. Solomon, JOSA B, 33, C160 (2016)

[2] O. Gazzano et al., Nature Communications, 4, 1425 (2013)

[3] O. Gazzano et al., In preparation (2016)

[4] O. Gazzano et al., Physical Review Letters, 110, 250501 (2013)

[5] T. Thomay, et al., Submitted (2016)

Contact : clement.faugeras@lncmi.cnrs.fr

Discipline évènement : (Physique)
Entité organisatrice : (LNCMI)
Nature évènement : (Séminaire)
Site de l'évènement : Polygone scientifique

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