Collisionally induced laser cooling of ultradense molecular gases

• Applicant: Professor Dr. Martin Weitz
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: from 2010 to 2017
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 174302509

While laser cooling of atoms is a very successful technique, such cooling of molecules has so far been an elusive goal. The aim of this project is to experimentally demonstrate the laser cooling of an ultradense molecular gas. We will use a technique that is complementary to earlier approaches and uses laser-induced transitions in a high pressure environment, with frequent molecule-buffer gas collisions shifting molecular transitions into resonance with a highly red detuned laser beam, while spontaneous decay occurs close to the unperturbed transition frequency. In such excitation cycles, we expect kinetic and internal molecular energy to be extracted from the probe ensemble. In preliminary experiments, our group has successfully demonstrated collisional redistribution cooling for an ultradense atomic ensemble with rubidium atoms and 230 bar of argon buffer gas. Due to the complex vibrational and molecular structure, whose characteristics in a high pressure buffer gas environment remain to be investigated, the application of redistribution cooling to molecules requires intense research. We foresee tantalizing applications of redistribution cooling in molecular quantum physics and a novel type of chemistry. Other applications can include optical chillers.

• DFG Programme: Reinhart Koselleck Projects