Food systems research in Ethiopia: 25 priority questions identified

Poster prepared for a share fair, Addis Ababa, May 201

Near-zero-energy end states in topologically trivial spin-orbit coupled superconducting nanowires with a smooth confinement

A one-dimensional spin-orbit coupled nanowire with proximity-induced pairing from a nearby s-wave superconductor may be in a topological nontrivial state, in which it has a zero energy Majorana bound state at each end. We find that the topological trivial phase may have fermionic end states with an exponentially small energy, if the confinement potential at the wire's ends is smooth. The possible existence of such near-zero energy levels implies that the mere observation of a zero-bias peak in the tunneling conductance is not an exclusive signature of a topological superconducting phase even in the ideal clean single channel limit.Comment: 4 pages, 4 figure

Pumped current and voltage for an adiabatic quantum pump

We consider adiabatic pumping of electrons through a quantum dot. There are two ways to operate the pump: to create a dc current ${\bar I}$ or to create a dc voltage ${\bar V}$. We demonstrate that, for very slow pumping, ${\bar I}$ and ${\bar V}$ are not simply related via the dc conductance $G$ as $\bar I = \bar V G$. For the case of a chaotic quantum dot, we consider the statistical distribution of ${\bar V} G - {\bar I}$. Results are presented for the limiting cases of a dot with single channel and with multichannel point contacts.Comment: 6 pages, 4 figure

A Food systems approach to healthier diets in Ethiopia

Poster prepared for a share fair, Addis Ababa, May 201

Rotating saddle trap as Foucault's pendulum

One of the many surprising results found in the mechanics of rotating systems is the stabilization of a particle in a rapidly rotating planar saddle potential. Besides the counterintuitive stabilization, an unexpected precessional motion is observed. In this note we show that this precession is due to a Coriolis-like force caused by the rotation of the potential. To our knowledge this is the first example where such force arises in an inertial reference frame. We also propose an idea of a simple mechanical demonstration of this effect.Comment: 13 pages, 9 figure