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Wavefunction collapse models modify Schrodinger's equation so that it describes the rapid evolution of a superposition of macroscopically distinguishable states to one of them. This provides a phenomenological basis for a physical…

Quantum Physics · Physics 2022-10-12 Brian Collett , Philip Pearle

We report video-microscopy measurements of the translational and rotational Brownian motions of isolated ellipsoidal particles in quasi-two-dimensional sample cells of increasing thickness. The long-time diffusion coefficients were measured…

Soft Condensed Matter · Physics 2009-03-10 Y. Han , A. Alsayed , M. Nobili , A. G. Yodh

Standard continuous time random walk (CTRW) models are renewal processes in the sense that at each jump a new, independent pair of jump length and waiting time are chosen. Globally, anomalous diffusion emerges through action of the…

Statistical Mechanics · Physics 2015-06-17 Johannes HP Schulz , Aleksei V Chechkin , Ralf Metzler

Continuous Time Random Walks (CTRWs) are jump processes with random waiting times between jumps. We study scaling limits for CTRWs where the distribution of jumps and waiting times is coupled and varies in space and time. Such processes…

Probability · Mathematics 2015-01-06 Peter Straka

We study noisy heterogeneous diffusion processes with a position dependent diffusivity of the form $D(x)\sim D_0|x|^\alpha$ in the presence of annealed and quenched disorder of the environment, corresponding to an effective variation of the…

Statistical Mechanics · Physics 2015-06-23 Andrey G. Cherstvy , Ralf Metzler

The ordinary subdiffusion equation, with a fractional time derivative of at most first order, describes a process in which the propagation velocity of diffusing molecules is unlimited. To avoid this non-physical property different forms of…

Statistical Mechanics · Physics 2026-05-27 Tadeusz Kosztołowicz , Aldona Dutkiewicz , Katarzyna D. Lewandowska

Many theoretical treatments of transport in heterogeneous Darcy flows consider advection only. When local-scale dispersion is neglected, flux-weighting persists over time; mean Lagrangian and Eulerian flow velocity distributions relate…

Fluid Dynamics · Physics 2024-07-25 Lian Zhou , Scott K. Hansen

Subdiffusion on graphs is often modeled by time-fractional diffusion equations, yet its structural and dynamical consequences remain unclear. We show that subdiffusive transport on graphs is a memory-driven process generated by a random…

Social and Information Networks · Computer Science 2026-01-22 Nikita Deniskin , Ernesto Estrada

Computer simulations were done of the mean square displacement (MSD) of tracer particles in colloidal gels formed by diffusion or reaction limited aggregation of hard spheres. The diffusion coefficient was found to be determined by the…

Soft Condensed Matter · Physics 2009-03-25 Sujin Babu , Jean Christophe Gimel , Taco Nicolai

The continuous time random walk (CTRW) approach has been widely applied to model large-scale non-Fickian transport in the flow through disordered media. Often, the underlying microscopic transport mechanisms and disorder characteristics are…

Fluid Dynamics · Physics 2024-03-12 Xiangnan Yu , Marco Dentz , HongGuang Sun , Yong Zhang

We study a class of random walk, the stored-energy-driven L\'evy flight (SEDLF), whose jump length is determined by a stored energy during a trapped state. The SEDLF is a continuous-time random walk with jump lengths being coupled with the…

Statistical Mechanics · Physics 2013-06-26 Takuma Akimoto , Tomoshige Miyaguchi

In a very long Gaussian polymer on time scales shorter that the maximal relaxation time, the mean squared distance travelled by a tagged monomer grows as ~t^{1/2}. We analyze such sub-diffusive behavior in the presence of one or two…

Statistical Mechanics · Physics 2011-11-10 Yacov Kantor , Mehran Kardar

We study a symmetric random walk (RW) in one spatial dimension in environment, formed by several zones of finite width, where the probability of transition between two neighboring points and corresponding diffusion coefficient are…

Statistical Mechanics · Physics 2017-04-03 A. V. Nazarenko , V. Blavatska

Diffusion behavior of Brownian particles in confined spaces was studied for the displacements notably shorter than the confinement size. The confinements, resembling structure of porous solids, were modeled using a spatially-varying…

Disordered Systems and Neural Networks · Physics 2016-11-24 Daniel Schneider , Rustem Valiullin , Nail Fatkullin

We investigate a single particle on a 3-dimensional, cubic lattice with a random on-site potential (3D Anderson model). We concretely address the question whether or not the dynamics of the particle is in full accord with the diffusion…

Statistical Mechanics · Physics 2010-05-05 Robin Steinigeweg , Jochen Gemmer

We show that the generalized diffusion coefficient of a subdiffusive intermittent map is a fractal function of control parameters. A modified continuous time random walk theory yields its coarse functional form and correctly describes a…

Chaotic Dynamics · Physics 2015-06-26 N. Korabel , A. V. Chechkin , R. Klages , I. M. Sokolov , V. Yu. Gonchar

Propagation in quantum walks is revisited by showing that very general 1D discrete-time quantum walks with time- and space-dependent coefficients can be described, at the continuous limit, by Dirac fermions coupled to electromagnetic…

Quantum Physics · Physics 2013-07-16 Fabrice Debbasch , Giuseppe Di Molfetta , David Espaze , Vincent Foulonneau

A standard approach to study time-dependent stochastic processes is the power spectral density (PSD), an ensemble-averaged property defined as the Fourier transform of the autocorrelation function of the process in the asymptotic limit of…

Statistical Mechanics · Physics 2019-09-04 Vittoria Sposini , Ralf Metzler , Gleb Oshanin

Heterogeneous diffusion with spatially changing diffusion coefficient arises in many experimental systems like protein dynamics in the cell cytoplasm, mobility of cajal bodies and confined hard-sphere fluids. Here, we showcase a simple…

Statistical Mechanics · Physics 2022-02-14 Prashant Singh

We investigate the ensemble and time averaged mean squared displacements for particle diffusion in a simple model for disordered media by assuming that the local diffusivity is both fluctuating in time and has a deterministic average growth…

Statistical Mechanics · Physics 2016-10-05 A. G. Cherstvy , R. Metzler