Thursday, June 10, 2010, 16:00
WHGA Auditorium
R. Bertlmann, University of Vienna
Abstract:
Entanglement is one of the most striking features of quantum theory and it
is the source of quantum information theory, a new discipline in physics, which
has developed very fast in the last decades. Whereas usually investigations
are performed with photons we show where entanglement occurs within particle
physics and demonstrate its importance there.
In particular, we explain the features of the "strange" kaon system as an example of an entangled meson-antimeson pair. The analogies and differences to spin-1/2 or photon systems are emphasized. We present a particular Bell inequality and show its remarkable connection to CP (charge-parity) violation.
We introduce the concept of entanglement witnesses, operators that are able to detect entangled states, and use them to find the geometric structure of the state space. A simple and nice geometry is demonstrated for the two-qubit states.
Finally, we consider the spin and momentum degrees of freedom of two massive spin-1/2 particles as a four-qubit system and show how entanglement changes between different partitions of the qubits, when seen by different relativistically moving observers.