@article{OstermeyerPuhlmannKorn2009,
  author    = {Ostermeyer, Martin and Puhlmann, Dirk and Korn, Dietmar},
  title     = {Quantum diffraction of biphotons at a blazed grating},
  issn      = {0740-3224},
  year      = {2009},
  abstract  = {Correlations between photons are interesting for a number of applications and concepts in metrology, in particular for resolution improvements in different methods of quantum imaging. We demonstrate the application of a blazed grating for the characterization of the degree of spatial correlation of biphotons. The biphotons are generated by type II parametric downconversion. Compared to an ordinary transmission grating, a blazed grating shows a high diffraction efficiency only for a single order of diffraction. Thus, higher intensities in the Fraunhofer far field behind the grating, and easier photon counting, can be achieved. The distribution of the two-photon rate in the Fraunhofer far field of the blazed grating can show one additional order of diffraction with a visibility related to the degree of correlation of the biphotons. The number of spatial modes that are populated by the biphoton beam can be directly altered in our experiments. The relation of the spatial mode order of the photon propagation to the observable degree of spatial correlation of the biphotons is investigated and related to the Schmidt number of spatially entangled modes.},
  language  = {en}
}
@article{OstermeyerKornPuhlmannetal.2009,
  author    = {Ostermeyer, Martin and Korn, Dietmar and Puhlmann, Dirk and Henkel, Carsten and Eisert, Jens},
  title     = {Two-dimensional characterization of spatially entangled photon pairs},
  issn      = {0950-0340},
  doi       = {10.1080/09500340903359962},
  year      = {2009},
  abstract  = {We characterize the entanglement in position and momentum of photon pairs generated in type-II parametric down- conversion. Coincidence maps of the photon positions in the near-field and far-field planes are observed in two transverse dimensions using scanning fiber probes. We estimate the covariance matrix of an effective two-mode system and apply criteria for entanglement based on covariance matrices to certify space-momentum entanglement. The role of higher- order spatial modes for observing spatial entanglement between the two photons is discussed.},
  language  = {en}
}