ua nt - p h / 05 09 19 5 v 1 2 8 Se p 20 05 Identical particles and entanglement ∗

ua nt - p h / 05 09 21 8 v 1 3 0 Se p 20 05 N - qubit entanglement via the J 2 y - type collective interaction

ar X iv : q ua nt - p h / 05 09 19 4 v 1 2 8 Se p 20 05 Nonlocality without inequalities ∗

We prove that every conceivable hidden variable model reproducing the quantum mechanical predictions of almost any entangled state must necessarily violate Bell’s locality condition. The proof does not involve the consideration of any Bell inequality but it rests on simple set theoretic arguments and it works for almost any noncompletely factorizable state vector associated to any number of par...

ar X iv : q ua nt - p h / 05 09 14 6 v 1 2 1 Se p 20 05 Engineering atom - atom thermal entanglement via two - photon process

We study the system that two atoms simultaneously interact with a single-mode thermal field via different couplings and different spontaneous emission rates when two-photon process is involved. It is found that we indeed can employ the different couplings to produce the atom-atom thermal entanglement in two-photon process. The different atomic spontaneous emission rates are also utilizable in g...

ar X iv : q ua nt - p h / 05 06 09 5 v 1 1 3 Ju n 20 05 Schmidt states and positivity of linear maps

Using pure entangled Schmidt states, we show that m-positivity of a map is bounded by the ranks of its negative Kraus matrices. We also give an algebraic condition for a map to be m-positive. We interpret these results in the context of positive maps as entanglement witnesses, and find that only 1-positive maps are needed for testing entanglement.

ua nt - p h / 05 05 09 8 v 1 1 3 M ay 2 00 5 Realization of the ” all - versus - nothing ” nonlocality test by adopting two - photon hyper - entanglement

We report the experimental realization and the characterization of polarization and momentum hyper-entangled two photon states, generated by a new parametric source of correlated photon pairs. By adoption of these states a successful " all versus nothing " test of quantum mechanics was performed. The two photon hyper-entangled states are expected to find at an increasing rate a widespread appli...