Stirring the quantum vacuum: Angular Casimir Momentum of a Landau Charge

International audienceWe consider the angular momentum of a charge q rotating in a homogeneous magnetic field and study the role of the electromagnetic quantum vacuum. Its orbital angular momentum is caused by the recoil of energetic vacuum photons that grows as n 2 , i.e. faster than the kinetic angular momentum −2n of a Landau level

Anderson Localization of Matter Waves in 3D Anisotropic Disordered Potentials

Using a cutoff-free formulation of the coherent transport theory, we show that the interference terms at the origin of localization strongly affect the transport anisotropy. In contrast to the common hypothesis, we then find that the anisotropies of incoherent and coherent diffusion are significantly different, in particular at criticality. There, we show that the coherent transport anisotropy is mainly determined by the properties of the disorder-averaged effective scattering medium while the incoherent transport contributions become irrelevant

Magneto-electric momentum transfer to atoms and molecules

We report the first observation of mechanical momentum transferred to atoms and molecules upon application of crossed electric and magnetic fields. We identify this momentum as the microscopic analogue of the classical Abraham force. Several predictions of additional magneto-electrically induced mechanical momentum are addressed. One of them, proposed to result from the interaction with the quantum vacuum, is experimentally refuted, others are found to be currently below experimental detection.Comment: 4 pages, 3 figures, one tabl

Giant fluctuations of topological charge in a disordered wave guide

We study the fluctuations of the total topological charge of a scalar wave propagating in a hollow conducting wave guide filled with scatterers inside. We investigate the dependence of the screening on the scattering mean free path and on the presence of boundaries. Near the cut-off frequencies of the wave guide, screening is strongly suppressed near the boundaries. The resulting huge fluctuations of the total topological charge are very sensitive to the disorder.Comment: 8 pages 5 figures, submitted to Waves in Random and Complex Medi

Quasi Two-dimensional Transfer of Elastic Waves

A theory for multiple scattering of elastic waves is presented in a random medium bounded by two ideal free surfaces, whose horizontal size is infinite and whose transverse size is smaller than the mean free path of the waves. This geometry is relevant for seismic wave propagation in the Earth crust. We derive a time-dependent, quasi-2D radiative transfer equation, that describes the coupling of the eigenmodes of the layer (surface Rayleigh waves, SH waves, and Lamb waves). Expressions are found that relate the small-scale fluctuations to the life time of the modes and to their coupling rates. We discuss a diffusion approximation that simplifies the mathematics of this model significantly, and which should apply at large lapse times. Finally, coherent backscattering is studied within the quasi-2D radiative transfer equation for different source and detection configurations.Comment: REVTeX, 36 pages with 10 figures. Submitted to Phys. Rev.

Observation of multifractality in Anderson localization of ultrasound

We report the first experimental observation of strong multifractality in wave functions at the Anderson localization transition in open three-dimensional elastic networks. Our results confirm the recently predicted symmetry of the multifractal exponents. We have discovered that the result of multifractal analysis of the real data depends on the excitation scheme used in the experiment.Comment: 4 pages, 3 figure