Le 26 mars à 10H en visioconférence : https://zoom.us/j/96448437376?pwd=K2ttYjg2N0RCN1llL0Q2WGZTU3Y1QT09

Single-Pass Generation and Detection of Ultrafast Multimode Squeezed Light

In this thesis, we present two experiments of generation of multimode squeezed states of light via spontaneous parametric down conversion (SPDC) pumped with an optical frequency comb. First, we built a setup using a bulk BBO crystal. Thanks to the non-collinear and single-pass configuration of the experiment, the quantum states are generated at a repetition rate of 156 MHz and feature spatio-spectral correlations. The states are building blocks of highly entangled states called dual-rail cluster states, which are useful for quantum information. Because of the configuration of the parametric process, the generated states are highly multimode both spatially and spectrally and they display a low level of squeezing par mode.

For that reason, we developed a new setup using waveguides of periodically-poled KTP to replace the bulk BBO crystal. Thanks to the increased nonlinearity, light confinement inside the waveguide and the use of quasi-phase matching, the squeezing per mode of the generated states should be increased.

In the meantime, we developed a wideband homodyne detector operating with pulsed light in order to perform pulse-by-pulse homodyne measurements. We present the features of such detectors as well as the challenges associated to pulsed light.