Hannover 2016 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 48: Ultra-cold atoms, ions and BEC III (with A)

Q 48.4: Talk

Thursday, March 3, 2016, 11:45–12:00, f107

Measurements of spectral functions of ultra-cold atoms in a speckle potential — •Vincent Denechaud, Valentin Volchkov, Mukhtar Musawwadah, Jérémie Richard, Alain Aspect, and Vincent Josse — Laboratoire Charles Fabry - Institut d’Optique, Palaiseau, France

We present a spectroscopic study of ultra-cold atomic states in a disordered potential created by a laser speckle. Atoms are first prepared in a spin state which is insensitive to disorder. In a second step, a radio-frequency spin-flip towards a disorder-sensitive spin state is performed. The transfer rate A(E,k) of such operation is referred to as spectral function, which correspond to the probability of populate an atomic state with a momentum k and an energy E within the disorder [1].

Measurements of such spectral function for various disorder configurations will be presented and discussed. We will highlight two kinds of regimes : the so-called "classical" disorder where the atomic states are shaped by the fluctuations of the random potential, and the "quantum" disorder where the states are dominated by tunelling effects. We will also explore peculiar features of spectral functions for a repulsive or an attractive speckle potential.

In principle, the spin-flip transfer allows us to create states with narrow energy distributions within the disorder. This paves the way to a precise study of the metal/insulator Anderson phase transition [2].

[1] M.I.Trappe et al, J.Phys.A: Math.Theor.48, 245102 (2015)

[2] A.Lagendijk et al, Physics Today, 62, 24 (2009)