ar X iv : q ua nt - p h / 06 02 22 6 v 1 2 8 Fe b 20 06 Weak Values , Pre - and Post - selection , and Contextuality

ua nt - p h / 06 02 22 6 v 2 2 8 M ar 2 00 6 Weak Values , Pre - and Post - selection , and Contextuality

By analyzing the concept of contextuality (e.g. Bell-Kochen-Specker) in light of post-selection, it is possible to assign definite values to observables in a new and surprising way. We present physical reasons for restrictions on these assignments. In addition, we show that when measurements are performed which do not disturb the pre-and post-selection (i.e. weak-measurements), then novel exper...

ar X iv : q ua nt - p h / 02 06 11 6 v 1 1 8 Ju n 20 02 Five Lectures On Dissipative Master Equations

ar X iv : q ua nt - p h / 06 06 17 6 v 1 2 1 Ju n 20 06 On quantum positive dynamical maps

The new arguments indicating that non-completely positive maps can describe open quantum evolution are given. This work was partially supported by KBN grant PB/1490/PO3/2003/25 and SCALA (IST-2004-015714) 1

ar X iv : q ua nt - p h / 06 02 15 4 v 1 1 7 Fe b 20 06 Geometric phases and criticality in spin systems

A general formalism of the relation between geometric phases produced by circularly evolving interacting spin systems and their criticality behavior is presented. This opens up the way for the use of geometric phases as a tool to study regions of criticality without having to undergo a quantum phase transition. As a concrete example a spin-1/2 chain with XY interactions is presented and the cor...

ar X iv : q ua nt - p h / 06 03 00 8 v 2 2 1 Ju n 20 06 ON POSITIVE DECOMPOSABLE MAPS

A partial characterization (a necessary condition for decompos-ability and a criterion for nondecomposability) of decomposable positive maps is given. Furthermore, a clarification of the structure of the set of positive maps is provided.