Distillability of Inseparable Quantum Systems

Abstract

We apply the inseparability criterion for $2 \times 2$ systems, local filtering and Bennett et al. purification protocol [Phys. Rev. Lett. {\bf 76}, 722 (1996)] to show how to distill {\it any} inseparable $2\times 2$ system. The extended protocol is illustrated geometrically by means of the state parameters in the Hilbert-Schmidt space.

Revtex, 4 pages (in twocolumn format), introduction and conclusion are slightly modified; one postscript figure available at request from fizrh@univ.gda.pl