https://doi.org/10.1140/epjd/e2008-00132-1
Polarization correlation in the two-photon decay of atomic hydrogen: nonlocality versus entanglement
1
Institut für Physik, Universität Kassel,
34132 Kassel, Germany
2
Physikalisches Institut, Universität Heidelberg, 69120 Heidelberg, Germany
3
Max-Planck-Institut
für Kernphysik, 69029 Heidelberg, Germany
4
Gesellschaft für Schwerionenforschung (GSI),
64291 Darmstadt, Germany
Corresponding authors: a tradtke@physik.uni-kassel.de - b surz@physi.uni-heidelberg.de
Received:
25
April
2008
Published online:
11
July
2008
From the work by Perrie et al. [Phys. Rev. Lett. 54, 1790 (1985)],
photon pairs from the 
(two-photon) decay of atomic
hydrogen are known to be quantum mechanically correlated. In these
experiments, the polarization states of the photons emitted in back-to-back
geometry were shown to violate the Bell inequality as a qualitative sign
of nonlocality and entanglement. In the present contribution, we analyze how
these nonlocal quantum correlations, as given by the violation of the Bell
inequality, differ from the concurrence as a true entanglement measure. Results
are shown for both quantifiers in dependence of the decay geometry and the
initial polarization of the atoms for the and
two-photon decay of atomic hydrogen. These results
display the difference between nonlocality and entanglement and, hence,
may stimulate further experiments on nonlocal quantum correlations in atomic
systems.
PACS: 32.10.-f – Properties of atoms / 31.10.+z – Theory of electronic structure, electronic transitions, and chemical binding / 03.67.Bg – Entanglement production and manipulation / 03.65.Ud – Entanglement and quantum nonlocality
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2008
