Abstract : The work presented in this thesis is devoted to the experimental study of the atomic dynamics in a dissipative optical lattice. We used pump-probe spectroscopy and atomic imagery techniques. We obtained information about the temperature of the atoms, their dynamics when they are trapped in the potential wells and the transport phenomena.
We report the direct observation of Brillouin propagation modes by imagery and we relate them to the optical resonances observed in pump-probe spectra. We demonstrate the existence of dark modes, for which a propagation mode is excited which cannot be detected by spectroscopy.
We use optical lattices as a model system for statistical physics. We demonstrate the occurrence of stochastic resonance for the excitation of the Brillouin propagation mode.
In the last part of the thesis, we report the observation of directed diffusion in a symmetric periodic potentiel. This is due to a temporal symmetry breaking of the system.