Licentiate thesis: High visibility six-photon entanglement

by Magnus Rådmark (Stockholm University, Department of Physics)

Friday 30 Jan 2009, 10:00 → 11:30 Europe/Stockholm

FB42

Entanglement is a key resource in many information schemes and in the last years the research on multi-qubit entanglement has drawn lots of attention. In this thesis the experimental generation and characterization of multi-qubit entanglement is presented. The qubits are implemented in the polarization degree of freedom of photons and we have prepared genuine entangled states of two, four and six photons. We emphasize that one type of states can be applied to e.g. decoherence-free encoding, quantum communication without sharing a common reference frame, quantum telecloning, secret sharing and remote state preparation schemes. In the experimental implementation we use a single source of entangled photon pairs and extract the first, second and third order parametric down-conversion. The multi-order processes are not entirely spontaneous, as we get the right states utilizing bosonic emission enhancement due to indistinguishability. Despite the achievement of six-photon entangled states, is the setup completely free from interferometric overlaps making it robust and contribution to high fidelities of the generated states. The analysis results of our experimental states are in very good agreement with theory and also show very high visibilities in their correlations.