Osnabrück 2002 – wissenschaftliches Programm

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Q: Quantenoptik

Q 433: Poster: Laser – Grundlagen und Anwendungen

Q 433.27: Poster

Donnerstag, 7. März 2002, 16:30–18:30, Schloss

A High-Finesse Cavity as a Beamsplitter in a Mach-Zehnder interferometer — •Thomas Legero, Stefan Kudera, Axel Kuhn, and Gerhard Rempe — Max-Planck-Institut für Quantenoptik, D-85748 Garching

We discuss a Mach-Zehnder interferometer with the first beamsplitter replaced by a high-finesse Fabry-Perot optical cavity. For such a setup, it is evident that transmission and reflection of the cavity have a direct influence on the visibility of the interference fringes at the output ports of the interferometer. We first analyzed the effect of the cavity parameters on the visibility, and finally we built a high-finesse cavity. It is 40 µm long with a finesse of 100000, mirror transmissions of 19 ppm (parts per million) and mirror absorption losses of 8 ppm for each reflection.

A single atom that is strongly coupled to the cavity will significantly influence its transmission [1], and the fringes observed at the output ports of the interferometer are expected to react on the atom’s presence. This should allow to use the interferometer to probe the entanglement of internal atomic states with the photon path in the interferometer [2]. If the which-way information is stored in the atomic state, no fringes are expected. However, in correlation with a suitable measurement performed on the atom that erases this information, fringes should reappear at the output ports of the interferometer with an expected visibility of 85 %.

[1] P. Münstermann et al., Optics Communications, 159, 63-67 (1999)

[2] K.M. Gheri and H.Ritsch, Phys.Rev.A 56 , 3187 (1997)