Selforganization, superradiance and lasercooling in cavities

Light forces on atoms are strongly modified in an optical resonator. In contrast to free space, the back-action of the particles on the field plays a central part in the coupled atom field dynamics. This opens new possibilities for controlled manipulation of polarizable particles in optical fields ranging from new cooling techniques to quantum gates. Many limitations of laser cooling are lifted as dissipation takes place predominantly via the cavity field and does not rely on atomic spontaneous emission. As all particles are simultaneously coupled to the same cavity field, it creates tailored long range atomic interactions. Several theoretical predictions as laser cooling without spontaneous emission, collective motion and lasing of a single atom in a high-Q cavity were recently successfully confirmed experimentally. As a new striking example numerical simulations predict self-organization of the atoms into regular patterns maximizing cooperative light scattering of light into the cavity. This formation of a regular spatial pattern starts above a certain threshold pump strength and particle number. Such collective inelastic scattering could be the basis of an even more efficient and wider applicable laser cooling technique. A central goal of this research project is to investigate cavity induced atomic interactions and in particular atomic selforganisation in more detail. What is required to start the selforganisation process and when does it yield a stable final equilibrium? How does the process scale with atom number, cavity volume and pump strength? What are the ultimate limits on forces and temperatures? Finding answers to these questions requires extending known theoretical approaches and models, going beyond previous numerical simulations in the semiclassical limit. In particular we plan to study selforganization as a new tool to cool molecules for which no other cooling technique exists. The process of superradiant cold molecule formation by cavity induced photo-associations could generate externally and vibrationally cold molecules. Extending the models to the quantum motion of ultracold atoms (BEC) in a cavity, self-organization could dynamically form macroscopic superpositions of the different final states via a stimulated coherent process. Even the ground state can be a superposition of macroscopically distinct atomic distributions. Adding cavity mediated interaction to atoms in optical lattices creates long range forces, which should lead to important changes of phase transitions properties.

Light forces on atoms are strongly modified in an optical resonator. In contrast to free space, the back-action of the particles on the field plays a central part in the coupled atom field dynamics. This opens new possibilities for controlled manipulation of polarizable particles in optical fields ranging from new cooling techniques to quantum gates. Many limitations of laser cooling are lifted as dissipation takes place predominantly via the cavity field and does not rely on atomic spontaneous emission. As all particles are simultaneously coupled to the same cavity field, it creates tailored long range atomic interactions. Several theoretical predictions as laser cooling without spontaneous emission, collective motion and lasing of a single atom in a high-Q cavity were recently successfully confirmed experimentally. As a new striking example numerical simulations predict self-organization of the atoms into regular patterns maximizing cooperative light scattering of light into the cavity. This formation of a regular spatial pattern starts above a certain threshold pump strength and particle number. Such collective inelastic scattering could be the basis of an even more efficient and wider applicable laser cooling technique. A central goal of this research project is to investigate cavity induced atomic interactions and in particular atomic selforganisation in more detail. What is required to start the selforganisation process and when does it yield a stable final equilibrium? How does the process scale with atom number, cavity volume and pump strength? What are the ultimate limits on forces and temperatures? Finding answers to these questions requires extending known theoretical approaches and models, going beyond previous numerical simulations in the semiclassical limit. In particular we plan to study selforganization as a new tool to cool molecules for which no other cooling technique exists. The process of superradiant cold molecule formation by cavity induced photo-associations could generate externally and vibrationally cold molecules. Extending the models to the quantum motion of ultracold atoms (BEC) in a cavity, self-organization could dynamically form macroscopic superpositions of the different final states via a stimulated coherent process. Even the ground state can be a superposition of macroscopically distinct atomic distributions. Adding cavity mediated interaction to atoms in optical lattices creates long range forces, which should lead to important changes of phase transitions properties.