EXPERIMENTAL ENTANGLEMENT WITNESS FAMILY MEASUREMENT AND THEORETICAL ASPECTS OF QUANTUM TOMOGRAPHY

Abstract

In the first part of the thesis, we report an experiment in which one determines, with least tomographic effort, whether an unknown two-photon polarization state is entangled or separable. The method measures whole families of optimal entanglement witnesses at once. We introduce adaptive measurement schemes that greatly speed up the entanglement detection. On average, only about three families need to be measured before the entanglement is detected. The second part studies some theoretical aspects of quantum tomography. In particular, we construct optimal error regions for quantum tomography experiment with additional unknown parameters. We also show how one uses ideas from quantum tomography to deduce a reasonable and consistent system-bath state. Such studies have consequences on the subsequent system dynamics.