Anderson Localization of ultracold atoms in optical disorder
Disorder lies at the heart of many fundamental phenomena in condensed matter systems, such as metal-insulator transition in amorphous electronic conductors, superfluidity in porous media, and possibly high-Tc superconductivity.
The celebrated Anderson localization (P. W. Anderson Phys. Rev. 109, 1492, 1958) is one of the most emblematic effect of the disorder. Indeed, it predicts that the disorder can completely freeze the motion of quantum particles, leading to a genuine metal-insulator transition. This intriguing effect results from the destructive quantum interferences between many scattering paths and is ubiquituous to wave physics. To date, Anderson localization has been observed with differents systems, for electronic or classical waves ( Lagendijk et al. Phys. Today August 2009, for a recent review). However, despite extensive theoretical and experimental efforts over the past 50 years, the precise understanding of this localization effect remains an exciting but formidable task, both for experiment and theory.
Ultracold atomic systems offers new approaches to these issues. In particular, their great promises have been demonstrated in our group by two landmarks experiments: the first demonstrations of Anderson localization with matter waves (1D and 3D) and direct signature of coherence via the coherent backscattering signal. We are currently working on a new method that will allow us to investigate the localization-delocalization quantum phase transition (Anderson transition) that occurs in 3D, the "graal" of the domain.