Distilling Gaussian states with Gaussian operations is impossible
Eisert J, Scheel S, Plenio M B
PHYSICAL REVIEW LETTERS  Volume: 89   Issue: 13     Article Number: 137903


Atomic entanglement near a realistic microsphere
Dung H T, Scheel S, Welsch D G, Knöll L
JOURNAL OF OPTICS B-QUANTUM AND SEMICLASSICAL OPTICS  Volume: 4   Issue: 3   Pages: S169-S175   Article Number: PII S1464-4266(02)29324-6