arXiv subjects

M. Trepanier

Publications and source records attributed to M. Trepanier.

2 recordsLinked to original sources

arXiv2013

Realization and modeling of rf superconducting quantum interference device metamaterials

We have prepared meta-atoms based on radio frequency superconducting quantum interference devices (RF SQUIDs) and examined their tunability with dc magnetic field, rf current, and temperature. RF SQUIDs are superconducting split ring resonators in which the usual capacitance is supplemented with a Josephson junction, which introduces strong nonlinearity in the rf properties. We find excellent agreement between the data and a model which regards the Josephson junction as the resistively and capacitively-shunted junction. A magnetic field tunability of 80 THz/Gauss at 12 GHz is observed, a total tunability of 56$%$ is achieved, and a unique electromagnetically-induced transparency feature at intermediate excitation powers is demonstrated for the first time. An RF SQUID metamaterial is shown to have qualitatively the same behavior as a single RF SQUID with regards to DC flux and temperature tuning.

cond-mat.supr-con↗

arXiv2010

Column collapse of granular rods

We find the collapse of columns of granular rods to show range of behaviors that depends on particle aspect ratio (length $L$ to diameter $d$) and initial pile geometry (height/radius). For all aspect ratios $L/d$ below 24 there exists a critical height at $L/4$ below which the pile acts as a solid, maintaining its initial shape, and a second critical height at $3L/4$ above which the pile always collapses like an ordinary granular material. Separating the critical heights is a transition region in which the probability of collapse increases linearly from 0 to 1. This behavior is independent of particle length, width, or aspect ratio. When the pile does collapse, the runoff radius $r_f$ scales as a power-law with dimensionless height $\tilde H$, agreeing with previous experiments on ordinary sand. For low piles the scaling is linear, with $r_f\sim \tilde H^{1.2\pm 0.1}$. Above a critical pile aspect ratio (pile height/radius) this switches to a square-root scaling, with $H^{0.6\pm0.1}$.

cond-mat.soft↗