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Étude théorique et expérimentale de superpositions quantiques cohérentes et d'états intriqués non-gaussiens de la lumière

Alexei Ourjoumtsev 1 
1 Laboratoire Charles Fabry de l'Institut d'Optique / Optique quantique
LCFIO - Laboratoire Charles Fabry de l'Institut d'Optique
Abstract : In this thesis, we develop new methods to generate and analyze non-classical states of the light for quantum information processing. We show that the tools of discrete variables, where light is described in terms of photons, can be combined with a continuous approach, where one considers the quadratures of the electromagnetic field, to efficiently create, transform and analyze complex quantum states. Using ultrashort light pulses, we prepared optical "Schrödinger cats", defined as quantum superpositions of coherent states. In this case the Wigner function, describing the quantum statistics of the electromagnetic field, differs from a classical probability distribution and takes negative values. Time-resolved homodyne tomography allowed us to realize the first experimental observation of this negativity for small free-propagating "Schrödinger kittens". Furthermore, we developed and experimentally demonstrated a protocol to prepare arbitrarily large "Schrödinger cat" states, opening a way towards numerous quantum information processing protocols. We have shown experimentally that conditional photon subtraction allows one to increase the entanglement of gaussian states. We used this method to entangle two initially independent distant light pulses, using a low-transmission quantum channel. This approach allows one to prepare strongly entangled states with negative Wigner functions between distant sites, as required for entanglement distillation and long-distance quantum communications.
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Contributor : Alexei Ourjoumtsev Connect in order to contact the contributor
Submitted on : Monday, June 30, 2008 - 5:25:31 PM
Last modification on : Sunday, June 26, 2022 - 11:48:22 AM
Long-term archiving on: : Saturday, November 26, 2016 - 12:29:39 AM


  • HAL Id : tel-00200715, version 2



Alexei Ourjoumtsev. Étude théorique et expérimentale de superpositions quantiques cohérentes et d'états intriqués non-gaussiens de la lumière. Physique Atomique [physics.atom-ph]. Université Paris Sud - Paris XI, 2007. Français. ⟨tel-00200715v2⟩



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