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Q: Fachverband Quantenoptik und Photonik

Q 56: Quanteninformation (Photonen und nichtklassisches Licht I)

Q 56.7: Vortrag

Freitag, 14. März 2008, 12:30–12:45, 1A

Spatial modes and spectral entanglement in PDC — •Andreas Eckstein, Andreas Christ, Thomas Lauckner, and Christine Siblerhorn — University Erlangen-Nuremberg, Max-Planck Research Group IOIP, Integrated Quantum Optics Group

We present the observation of a picosecond beating in a Hong-Ou-Mandel (HOM) type experiment. To study the HOM interference, we implemented a PDC process in a PPKTP waveguide, pumped by a picosecond laser at 404nm. Both signal and idler photons are fed into a balanced beamsplitter, and coincident photons from its output ports are detected. Instead of a gaussian HOM dip, we observe a gaussian-enveloped beating signature of coincidence events. Unlike the experiment in [1], our setup exhibits anti-bunching without spectrally restricting the detector response function.

We attribute this behavior the fact that our waveguide is multimoded in the pump regime. The superposition of spatial pump modes inside the waveguide is translated into a frequency correlation between signal and idler photons via modal dispersion. Owing to the broadband nature of the PDC-generated photons, we propose a definition for broadband mode entanglement and explore the feasibility of this anti-bunching effect as an entanglement witness.

[1] Hong, C. K., Ou, Z. Y., and Mandel, L. Phys. Rev. Lett. 59(18), 2044*2046 (1987).