Long-range interactions and collective effects in degenerate quantum gases coupled to the optical modes of a high-finesse ring cavity

• Applicant: Professor Dr. Philippe Courteille
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: from 2005 to 2010
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 12590509

The theme of our research project are long-range correlations and collective effects in the interaction of light with atoms. Many interesting aspects of collective interactions emerge only with cold atoms. The collective atomic recoil laser (CARL) first demonstrated by our research group is a good example: The device is based on cooperative scattering of light by cold atoms located inside a high-finesse ring cavity. However, a whole new range of phenomena is expected at even lower temperatures, in particular for ultra-cold coherent matter waves or Bose-Einstein condensates (BEC).BECs interacting with optical ring cavities have never been investigated, although this system is of fundamental importance: The slow decay of the field mode in high-finesse cavities can be harnessed to exert friction forces on BECs even on superfluid BECs. It is part of our research plans to show that the friction forces can give rise to novel cooling procedures for BECs and even synchronize the wavefunctions of initially independent BECs, thus leading to their fusion.BECs irradiated by light can develop interatomic dipole-dipole forces. The forces are predicted to give rise to spectacular phenomena. Prominent examples are self-gravitation of BECs on a microscopic scale, roton-resonances in the quasiparticle excitation spectrum or spatial self-organization involving novel types of quantum phase transitions. We plan to study the close connection between effects due to dipole-dipole interaction and CARL. Finally, CARL is intrinsically related to the phenomenon of superradiant Rayleigh scattering observed with BECs. The use of a ring cavity will allow us study new facettes of Rayleigh scattering in regimes, where the controversial nature of the relationship will become clear.

• DFG Programme: Research Grants
• Participating Person: Professor Dr. Claus Zimmermann