Generation of the Bound Entangled Smolin State and Entanglement Witnesses for Low-Dimensional Unitary Invariant States

• Main Author: Nordling, Emil
• Format: Others
• Language: English
• Published: Uppsala universitet, Teoretisk fysik 2010
• Subjects: quantum mechanics; quantum information science; entanglement; photonics; Smolin state; unitary invariant states
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-130039

Quantum entanglement is employed as a resource throughout quantum information science. However, before entanglement can be put to intelligent use, the issues of its production and detection must be considered. This thesis proposes four schemes for producing the bound entangled Smolin state. Three of these schemes produce the Smolin state by means of general quantum gates acting on different initial states - an all-zero state, a GHZ-state and two combined Bell states. The fourth scheme is based on one-qubit operations acting on two-photon states produced by SPDC. Furthermore, a maximum overlap entanglement witness detecting entanglement in the Smolin state is derived. This witness is measurable in three measurement settings with the maximal noise tolerance p=2/3. Lastly, simplified entanglement witnesses for the 4-, 6- and 8-qubit unitary invariant states are derived. These witnesses are measurable in three measurement settings with noise tolerances p=0.1802..., p=0.1502... and p=0.0751..., respectively.