Physical Sciences and Mathematics Commons^™

Dynamical Conductivity At The Dirty Superconductor-Metal Quantum Phase Transition, Adrian Del Maestro, Bernd Rosenow, Jose A. Hoyos, Thomas Vojta

Physics Faculty Research & Creative Works

We study the transport properties of ultrathin disordered nanowires in the neighborhood of the superconductor-metal quantum phase transition. To this end we combine numerical calculations with analytical strong-disorder renormalization group results. The quantum critical conductivity at zero temperature diverges logarithmically as a function of frequency. In the metallic phase, it obeys activated scaling associated with an infinite-randomness quantum critical point. We extend the scaling theory to higher dimensions and discuss implications for experiments.

Fluctuations And Pattern Formation In Self-Propelled Particles, Shradha Mishra, Aparna Baskaran, M. Cristina Marchetti

Physics - All Scholarship

We consider a coarse-grained description of a system of self-propelled particles given by hydrodynamic equations for the density and polarization fields. We find that the ordered moving or flocking state of the system is unstable to spatial fluctuations beyond a threshold set by the self-propulsion velocity of the individual units. In this region, the system organizes itself into an inhomogeneous state of well-defined propagating stripes of flocking particles interspersed with low density disordered regions. Further, we find that even in the regime where the homogeneous flocking state is stable, the system exhibits large fluctuations in both density and orientational order. …

Nonequilibrium Statistical Mechanics Of Self-Propelled Hard Rods, Aparna Baskaran, M. Cristina Marchetti

Physics - All Scholarship

Using tools of nonequilibirum mechanics, we study a model of self-propelled hard rods on a substrate in two dimensions to quantify the interplay of self-propulsion and excluded-volume effects. We derive of a Smoluchowski equation for the configurational probability density of self-propelled rods that contains several modifications as compared to the familiar Smoluchowski equation for thermal rods. As a side-product of out work, we also present a purely dynamical derivation of the Onsager form of the mean field excluded volume interaction among thermal hard rods.

The Tangled Tale Of Phase Space, David D. Nolte

David D Nolte