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Q: Fachverband Quantenoptik und Photonik

Q 23: Quanteninformation: Photonen II

Q 23.7: Vortrag

Dienstag, 3. März 2009, 15:30–15:45, VMP 6 HS-D

Fs-pulsed UV enhancement cavity used as a high power entanglement source — •Roland Krischek^{1, 2}, Witlef Wieczorek^{1, 2}, Akira Ozawa¹, Nikolai Kiesel^{1, 2}, Patrick Michelberger^{1, 2}, Thomas Udem¹, and Harald Weinfurter^{1, 2} — ¹Max-Planck-Institut für Quantenoptik, D-85748 Garching, Germany — ²Departement für Physik, Ludwig-Maximilians-Universität München, D-80799 München, Germany

The process of pulsed spontaneous parametric down conversion in combination with linear optics is successfully used for observing polarization entangled multi-photon states. However, when using commercial high power mode locked lasers, such experiments are limited by very low count rates resulting in very long measurement times for six-photon states already.

Here, we present the first UV femtosecond enhancement cavity designed to boost the photon count rate of down conversion experiments. To this end, the circulating pulses inside the cavity are resonantly enhanced by up to a factor of 18, which gives more than 10W UV power (at lambda = 390nm). Compared to today's available mode locked lasers this is one order of magnitude improvement. Due to the relatively low detection efficiency, our experiments are now only limited by additional noise from higher order emissions. The next step is thus to utilize the intrinsic spatial mode filter of the cavity to improve the collection efficiency above current state of the art values. We demonstrate the performance of our experiment with first results on the Dicke-state with six-photons.