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Full-Text Articles in Physics
Simulation Of Coherent Remission In Planar Disordered Medium, Pablo Jara-Palacios, Ho Chun Lin, Chia Wei Hsu, Hui Cao, Alexey Yamilov
Simulation Of Coherent Remission In Planar Disordered Medium, Pablo Jara-Palacios, Ho Chun Lin, Chia Wei Hsu, Hui Cao, Alexey Yamilov
Physics Faculty Research & Creative Works
Waves remitted from a scattering medium carry information that can be used for non-invasive imaging and sensing. Such techniques are usually limited by a low photon budget. Recent progress in optical wavefront shaping has enabled coherent control with an order-of-magnitude enhancement of remission [1]. This experimental study necessitated increasingly demanding numerical simulations. Extending this line of research requires more sophisticated computational techniques capable of simulating multiple instances of even larger systems. Here, we demonstrate that remission geometry can be efficiently simulated using a novel open-source software package [2] Maxwell's Equations Solver with Thousands of Inputs (MESTI). To verify its numerical …
Probability Density Of The Fractional Langevin Equation With Reflecting Walls, Thomas Vojta, Sarah Skinner, Ralf Metzler
Probability Density Of The Fractional Langevin Equation With Reflecting Walls, Thomas Vojta, Sarah Skinner, Ralf Metzler
Physics Faculty Research & Creative Works
We investigate anomalous diffusion processes governed by the fractional Langevin equation and confined to a finite or semi-infinite interval by reflecting potential barriers. As the random and damping forces in the fractional Langevin equation fulfill the appropriate fluctuation-dissipation relation, the probability density on a finite interval converges for long times towards the expected uniform distribution prescribed by thermal equilibrium. In contrast, on a semi-infinite interval with a reflecting wall at the origin, the probability density shows pronounced deviations from the Gaussian behavior observed for normal diffusion. If the correlations of the random force are persistent (positive), particles accumulate at the …
Fractional Brownian Motion With A Reflecting Wall, Alexander H. O. Wada, Thomas Vojta
Fractional Brownian Motion With A Reflecting Wall, Alexander H. O. Wada, Thomas Vojta
Physics Faculty Research & Creative Works
Fractional Brownian motion, a stochastic process with long-time correlations between its increments, is a prototypical model for anomalous diffusion. We analyze fractional Brownian motion in the presence of a reflecting wall by means of Monte Carlo simulations. Whereas the mean-square displacement of the particle shows the expected anomalous diffusion behavior (x2) ~ tα, the interplay between the geometric confinement and the long-time memory leads to a highly non-Gaussian probability density function with a power-law singularity at the barrier. In the superdiffusive case α > 1, the particles accumulate at the barrier leading to a divergence of the …
Position-Dependent Diffusion Of Light In Disordered Waveguides, Alexey Yamilov, Raktim Sarma, Brandon Redding, Ben Payne, Heeso Noh, Hui Cao
Position-Dependent Diffusion Of Light In Disordered Waveguides, Alexey Yamilov, Raktim Sarma, Brandon Redding, Ben Payne, Heeso Noh, Hui Cao
Physics Faculty Research & Creative Works
We present direct experimental evidence for position-dependent diffusion in open random media. The interference of light in time-reversed paths results in renormalization of the diffusion coefficient, which varies spatially. To probe the wave transport inside the system, we fabricate two-dimensional disordered waveguides and monitor the light intensity from the third dimension. Change the geometry of the system or dissipation limits the size of the loop trajectories, allowing us to control the renormalization of the diffusion coefficient. This work shows the possibility of manipulating wave diffusion via the interplay of localization and dissipation.
Adiabatic-Nonadiabatic Transition In The Diffusive Hamiltonian Dynamics Of A Classical Holstein Polaron, Alex A. Silvius, Paul Ernest Parris, Stephan De Bièvre
Adiabatic-Nonadiabatic Transition In The Diffusive Hamiltonian Dynamics Of A Classical Holstein Polaron, Alex A. Silvius, Paul Ernest Parris, Stephan De Bièvre
Physics Faculty Research & Creative Works
We study the Hamiltonian dynamics of a free particle injected onto a chain containing a periodic array of harmonic oscillators in thermal equilibrium. The particle interacts locally with each oscillator, with an interaction that is linear in the oscillator coordinate and independent of the particle's position when it is within a finite interaction range. At long times the particle exhibits diffusive motion, with an ensemble averaged mean-squared displacement that is linear in time. The diffusion constant at high temperatures follows a power law D~T 5/2 for all parameter values studied. At low temperatures particle transport changes to a hopping process …