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Q: Fachverband Quantenoptik und Photonik

Q 63: Quantengase (Wechselwirkungseffekte II / Spinorgase)

Q 63.2: Talk

Friday, March 14, 2008, 14:15–14:30, 3G/H

Cavity QED with a Bose-Einstein Condensate — •Ferdinand Brennecke, Tobias Donner, Stephan Ritter, Thomas Bourdel, Michael Köhl, Christine Guerlin, and Tilman Esslinger — Institute for Quantum Electronics, ETH Zürich, Switzerland

Cavity quantum electrodynamics (cavity QED) studies the coherent interaction of light and matter inside a high-finesse resonator. One of the main challenges in present experiments within the optical regime of cavity QED is to achieve a deterministic coupling strength between atoms and light, which in particular requires high control over the atomic external degrees of freedom. Using a Bose-Einstein condensate (BEC), we enter a new regime of cavity QED where all atoms couple identically to the cavity field. Here we present a measurement of the energy spectrum of this strongly coupled system in the low excitation limit. Due to a collective coupling of several GHz we observe a significant coupling of the BEC to higher-order transverse cavity modes. The strong coupling even of a single atom to the cavity mode offers the possibility to detect and manipulate a minority component of atoms in a different hyperfine state embedded within a BEC. Besides its relevance to the field of quantum information processing, the presented system offers a variety of interesting phenomena expected in the many-body physics of quantum gases within a quantum optical lattice. In contrast to the case of optical lattice potentials provided by strong laser fields, here the light field itself becomes a dynamical quantity depending on the atomic distribution, which leads to substantial cavity-mediated long-range interactions between the atoms.