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Biomedical subjects

B A van Tiggelen

Publications and source records attributed to B A van Tiggelen.

13 recordsLinked to original sources
PubMed2006

Fluctuations of local density of states and C0 speckle correlations are equal.

We establish a conceptual relation between the fluctuations of the local density of states (LDOS) and the intensity correlations in speckle patterns resulting from the multiple scattering of waves in random media. We show that among the known types of speckle correlations (C1, C2, C3, and C0) only contributes to LDOS fluctuations in the infinite medium. We propose to exploit the equivalence of LDOS fluctuations and the C0 intensity correlation as a "selection rule" for scattering processes contributing to C0.

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PubMed2006

Momentum transfer from quantum vacuum to magnetoelectric matter.

A recent publication [Phys. Rev. Lett. 92, 020404 (2004)] raises the possibility of momentum transfer from zero-point quantum fluctuations to matter, controlled by applied electric and magnetic fields. We present a Lorentz-invariant description using field-theoretical regularization techniques. We find no momentum transfer for homogeneous media, but predict a very small transfer for a Casimir-type geometry.

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PubMed2006

Dynamics of Anderson localization in open 3D media.

We develop a self-consistent theoretical approach to the dynamics of Anderson localization in open three-dimensional (3D) disordered media. The approach allows us to study time-dependent transmission and reflection, and the distribution of decay rates of quasimodes of 3D disordered slabs near the Anderson mobility edge.

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PubMed2004

Mesoscopic correlation with polarization rotation of electromagnetic waves.

Mesoscopic correlations are observed in the polarization of microwave radiation transmitted through a random waveguide. These measurements, supported by diagrammatic theory, permit an unambiguous decomposition of the intensity correlation function of a vector wave into short, long, and infinite range components. Infinite range correlation that leads to universal conductance fluctuations is measured and found to be in agreement with calculations. The long and infinite range components include nonuniversal frequency-independent terms associated with coupling into and out of the sample.

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PubMed2004

Dynamics of weakly localized waves.

We develop a transport theory to describe the dynamics of (weakly) localized waves in a quasi-1D tube geometry both in reflection and in transmission. We compare our results to recent experiments with microwaves and to other theories, such as random matrix theory and supersymmetric theory.

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PubMed2004

Probing Anderson localization of light via decay rate statistics.

We have studied the distribution of resonance widths P(Gamma) in one-, two-, and three-dimensional multiple light scattering systems. P(Gamma) should follow a universal power law P(Gamma) approximately Gamma(-1) in the localized regime as confirmed by extensive numerical calculations. This behavior can be interpreted as an unambiguous signature of exponential Anderson localization of light in open systems.

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PubMed2003

Green function retrieval and time reversal in a disordered world.

We apply the theory of multiple wave scattering to two contemporary, related topics: imaging with diffuse correlations and stability of the time reversal of diffuse waves, using equipartition, coherent backscattering, and frequency speckles as fundamental concepts.

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PubMed2002

Magnetochiral scattering of light: optical manifestation of chirality.

We have investigated multiple scattering of light in systems subject to magnetochiral (MC) effects. Our medium consists of magneto-optically active dipoles placed in a chiral geometry under the influence of an external magnetic field. We have calculated the total and the differential scattering MC cross sections of this system, explicitly showing that they are proportional to pseudoscalar quantities. This provides an optical measure for the degree of chirality, a pseudoscalar g, of an arbitrary geometrical configuration of scatterers based on its scattering properties. We have calculated g for some simple chiral systems and we have even used it to probe the degree of optical chirality of random systems. Finally, we have compared g with other recently defined chiral measures in literature.

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PubMed2002

Multiple scattering of seismic waves.

We present theory and numerical simulations to model seismic wave propagation in the Earth crust. We compare them to observations made in Mexico.

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PubMed2001

Observation of equipartition of seismic waves.

Equipartition is a first principle in wave transport, based on the tendency of multiple scattering to homogenize phase space. We report observations of this principle for seismic waves created by earthquakes in Mexico. We find qualitative agreement with an equipartition model that accounts for mode conversions at the Earth's surface.

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PubMed2001

Coherent backscattering of elastic waves: specific role of source, polarization, and near field.

Calculation of coherent backscattering of elastic waves in an infinite isotropic random medium is presented. Despite the simplicity of this geometry, this calculation highlights several specific aspects for seismic detection: near field detection, polarization, and the symmetry of the source. Line profiles and enhancement factors are seen to be time independent and are calculated for kinetic, shear, and compressional energy.

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PubMed1999

Delay-time statistics for diffuse waves.

We formulate a theory for the statistics of the dynamics of a classical wave propagating in random media by analyzing the frequency derivative of the phase under the assumption of a Gaussian process. We calculate frequency correlations and probability distribution functions of dynamical quantities, as well the first non-Gaussian C2 correction. In A. Z. Genack, P. Sebbah, M. Stoytchev, and B. A. van Tiggelen, Phys. Rev. Lett. 82, 715 (1999), microwave measurements have been performed to which this theory applies.

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