PhD Thesis Quantum Optics
This work aims at exploiting the quantum properties of light in order to develop new communication devices. The study is devoted to the quadrature components (quantum continuous variables) of a single mode of the electromagnetic field in the pulsed regime. A quantum key distribution protocol using coherent states has been demonstrated, and opens the way for practical high-rate quantum cryptography devices.
In order to study the use of quantum specificities such as squeezing and entanglement, we have developed a new source of pulsed squeezed states and entangled states. This source is based on the nonlinear conversions of ultrashort pulses. We also describe the first observation of a degaussification protocol, that maps individual pulses of squeezed vacuum onto non-Gaussian states. Finally, we study some optical set-ups allowing for a loophole-free Bell test using continuous variables and efficient homodyne detections.
Quantum information - quantum communication - quantum cryptography - continuous variables - pulsed homodyne detection - femtosecond pulses - parametric amplification - squeezed states - non-Gaussian states - entanglement - Bell's inequalities