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Theses

On-chip generation of high-dimensional entangled states of light

Abstract : Nonclassical states of light are key resources for quantum information technologies thanks to their easy transmission, robustness to decoherence and variety of degrees of freedom to encode information. In this context, this PhD thesis is dedicated to the development of novel semiconductor photon pair sources. Exploiting the high flexibility offered by spontaneous parametric down conversion (SPDC) in AlGaAs waveguides, we demonstrate the generation and the engineering of high-dimensional nonclassical states of light encoded in frequency. First, we employ a source based on a counter-propagating phase-matching scheme and demonstrate that tailoring the spatial profile (intensity and phase) of the pump beam enables the control of the photon pair spectral correlations and wavefunction symmetry directly at the generation stage, without any post-selection. In particular, tuning the pump beam waist allows to produce correlated, anti-correlated and separable frequency states, while modifying the spatial phase profile allows to switch between symmetric and antisymmetric spectral wavefunctions and to modify the exchange statistics of the photons, as evidenced measured via Hong-Ou-Mandel interferometry. We also investigate more complex quantum states: we demonstrate that this source, thanks to its geometry and to an anti-reflection coating, can also emit photon pairs entangled in a hybrid polarization/frequency degree of freedom. We then start the development of a novel device formed by a lattice of parallel co-propagating nonlinear waveguides, design to emit spatially entangled photon pairs via cascaded quantum walks. We report the optimization of its clean room fabrication processes and first optical characterizations of this novel device.
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Submitted on : Wednesday, September 1, 2021 - 11:04:13 AM
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  • HAL Id : tel-03330746, version 1

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Saverio Francesconi. On-chip generation of high-dimensional entangled states of light. Physics [physics]. Université Paris Cité, 2020. English. ⟨NNT : 2020UNIP7191⟩. ⟨tel-03330746⟩

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