Collective Atomic Recoil Lasing and Superradiant Rayleigh Scattering in a high-Q ring cavity

Abstract

Cold atoms in optical high-Q cavities are an ideal model system for long-range interacting particles. The position of two arbitrary atoms is, independent on their distance, coupled by the back-scattering of photons within the cavity. This mutual coupling can lead to collective instability and self-organization of a cloud of cold atoms interacting with the cavity fields. This phenomenon (CARL, i.e. Collective Atomic Recoil Lasing) has been discussed theoretically for years, but was observed only recently in our lab. The CARL-effect is closely linked to superradiant Rayleigh scattering, which has been intensely studied with Bose-Einstein condensates in free space. By adding a resonator the coherence time of the system, in which the instability occurs, can be strongly enhanced. This enables us to observe cavity-enhanced superradiance with both Bose-Einstein condensates and thermal clouds and allows us to close the discussion about the role of quantum statistics in superradiant scattering.

Nonequilibrium statistical mechanics of systems with long-range interactions

“…Examples of such systems include galaxies and globular clusters [56][57][58][59][60][61][62][63][64], two-dimensional and geophysical flows and vortex models [18,[65][66][67][68][69][70], quantum spin models [71], dipolar excitons [72], cold atom models [73], as well as magnetically confined plasmas [23,[74][75][76]. In order to predict the behavior of systems with short-range forces we can rely on thermodynamics and statistical mechanics both of which, however, fail for systems with LR interactions.…”

Roton-Type Mode Softening in a Quantum Gas with Cavity-Mediated Long-Range Interactions

“…A different approach to long-range interactions in cold gases makes use of the radiative coupling between electric dipoles induced by off-resonant laser light, which has been shown theoretically to cause a roton-like minimum in the energy spectrum of a BEC [8,10]. A large enhancement of such radiative coupling is achieved by placing the dipoles into an optical resonator, which leads to strong global atom-atom interactions [17,18,20,33].…”

Chaos and relaxation to equilibrium in systems with long-range interactions

“…Such systems are characterized by an interparticle potential that decays with distance as 1/r α , where α < d and d is the dimensionality of the embedding space [1][2][3]. Into this category fall galaxies and globular clusters [4,5], twodimensional fluid models [6], confined plasmas [7], quantum spin models [8], dipolar systems [9], cold atoms models [10], and colloidal particles at interfaces [11]. LR interacting systems are found to have a complex relaxation process, with distinct time scales.…”