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Q: Fachverband Quantenoptik und Photonik

Q 64: Quanteneffekte: Verschränkung

Q 64.3: Talk

Friday, March 6, 2009, 14:30–14:45, VMP 6 HS-D

2D Spatial Entanglement Characterization of Biphotons — •Dietmar Korn, Dirk Puhlmann, Sebastian Wander, Robert Elsner, and Martin Ostermeyer — Institute for Physics and Astronomy, University of Potsdam, Potsdam, Germany

Several schemes in quantum imaging rely on multi-photon absorption. Therefore a detailed knowledge of the temporal and spatial correlations of the photons used is desired.

We investigate the correlations of space-momentum entangled biphotons. A pair of photons is generated by type II parametric down conversion and subsequently a biphoton is created utilizing a Hong-Ou-Mandel interference. To obtain a complete mapping of the biphoton’s space and momentum cross sections, the near and far field of the crystal is analysed by a Hanbury-Brown-Twiss like setup with two single mode fiber probes, one in each path behind a beam splitter.

The fibre probes, having a mode-field diameter of 5 µ m, can be moved independently over an area of 20 µ m x 20 µ m onto which the near / far field of the crystal plane has been mapped. By evaluating the coincidence photon count rate with respect to the probe positions [1] a product of variances in space and momentum can be derived which shows a strong violation of the classical correlation bound [2].

[1] Howell, J.C. et al., Phys. Rev. Lett. 92, 210403(2004).

[2] Mancini, S. et al., Phys. Rev. Lett. 88, 120401(2002).