Direct weak localization signature with ultracold atoms: the CBS revival

Ultracold atomic systems in presence of disorder have attracted a lot of interest over the past decade, in particular to study the physics of Anderson localization (AL) in a renewed perspective. Landmark experiments have been demonstrated, in 1D \cite{Billy,Roati} and 3D \cite{Kondov,Jendrzejewskia,Semeghini} geometries. However many challenges remain and new ideas have emerged, as for instance the search for original signatures of Anderson localization in momentum space \cite{Karpiuk}. \\ Here I will describe our progresses along that line where a weak localization effect has been directly observed, i.e. the Coherent Backscattering (CBS) phenomenon \cite{Jendrzejewskib}. In particular I will report on the recent observation of suppression and revival of CBS when a controlled dephasing kick is applied to the system \cite{Muller}. This observation demonstrates a novel and general method, introduced by T. Micklitz and coworkers \cite{Micklitz}, to study probe phase coherence in disordered systems by manipulating time reversal symmetry. J. Billy \textit{et al.,}, Nature \textbf{453}, 891 (2008). G. Roati \textit{et al.,}, Nature \textbf{453}, 895 (2008). S. Kondov \textit{et al.,} Science \textbf{334}, 66 (2011). F. Jendrzejewki \textit{et al.,} \textit{Nat. Phys. }\textbf{8}, 398 (2012). S. Semeghini \textit{et al.} \textit{Nat. Phys. }\textbf{11}, 554 (2015). T. Karpiuk \textit{et al.}, \textit{Phys. Rev. Lett.} \textbf{109,} 190601 (2012). F. Jendrzejewski \textit{et al., Phys. Rev. Lett. }\textbf{109}, 195302 (2012). K. M\"{u}ller \textit{et al., Phys. Rev. Lett.} \textbf{114}, 205301 (2015). T. Micklitz\textit{ et al}., \textit{Phys. Rev. B} \textbf{91}, 064203 (2015).