Hannover 2013 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 42: Ultra-cold atoms, ions and BEC V (with A)
Q 42.5: Vortrag
Mittwoch, 20. März 2013, 15:15–15:30, B 302
Coherent Backscattering of Ultracold Atoms — •Fred Jendrzejewski1,3, Kilian Müller1, Jeremie Richard1, Philippe Bouyer2, Alain Aspect1, and Vincent Josse1 — 1Laboratoire Charles Fabry, Palaiseau, France — 2LP2N, Talence, France — 3Joint Quantum Institute, Gaithersburg, USA
Quantum interference effects play a fundamental role in our understanding of quantum transport through disordered media, as it can lead to the suppression of transport, i.e. Anderson Localization. Recently it became possible to directly observe Anderson Localization with ultracold atoms. Convincing as they are, none of these experiments includes a direct evidence of the role of coherence.
For weak disorder, a first order manifestation of coherence is the phenomenon of coherent backscattering (CBS), i.e. the enhancement of the scattering probability in the backward direction, due to a quantum interference of amplitudes associated with two opposite multiple scattering paths.
In this talk, I present our work on the direct observation of such a CBS peak. Launching atoms with a well-defined momentum in a laser speckle disordered potential, we follow the progressive build up of the momentum scattering pattern, consisting of a ring associated with multiple elastic scattering, and the CBS peak in the backward direction. The observation of the CBS peak is a smoking gun of the existence of quantum coherence in quantum transport in disordered media.