Quantum mechanics

Ecology

Biology

Dynamics (music)

Radiation

Embedded system

Scattering

Atomic physics

Computer science

Acoustics

Scaling

Trapping

Laser

Physics

Dipole

Mathematics

Optics

Atom (system on chip)

Geometry

Radiation trapping

New Journal of Physics

We experimentally and numerically study the temporal dynamics of light scattered by large clouds of cold atoms after the exciting laser is switched off in the low intensity (linear optics) regime. Radiation trapping due to multiple scattering as well as subradiance lead to decay much slower than the single atom fluorescence decay. These two effects have already been observed separately, but the interplay between them remained to be understood. Here, we show that with well chosen parameters of the driving field, the two effects can occur at the same time, but follow different scaling behaviors. The subradiant decay is observed at late time and its rate is independent of the detuning, while the radiation trapping decay is observed at intermediate time and depends on the detuning through the optical depth of the sample. Numerical simulations based on random walk process and coupled-dipole equations support our interpretations. Our study clarifies the different interpretations and physical mechanisms at the origin of slow temporal dynamics of light in cold atoms.

Subradiance and radiation trapping in cold atoms