Publications by Benjamin Apffel

The spinorial ball: A macroscopic object of spin-1/2

In quantum physics lectures, half-integer spins are generally introduced as "objects that do not come back to their original state after one full turn but that do after two." As a consequence, students often consider this behavior to be purely quantum mech ...

AIP Publishing2025

Motion of a floating sphere pulled by a string and induced flows

Romain Christophe Rémy Fleury, Benjamin Apffel

We study in this article the motion of a floating ball attached to a soft string set in circular motion through its other end. Although simple, the system exhibits rich dynamics that we investigate experimentally and theoretically. At low rotation speeds, ...

2025

Science of a coffee cup: A physicist walks into a bar…

Romain Christophe Rémy Fleury, Benjamin Apffel

… and annoys everyone with unsolicited experiments. The present paper proposes a short pedagogical review of the various phenomena that can be observed in a coffee cup with little to no equipment. The physical domains spanned include acoustics, optics, and ...

2025

Experimental observation of parabolic wakes in thin plates

Romain Christophe Rémy Fleury, Benjamin Apffel, Aleksi Antoine Bossart, Janez Rus, Matthieu Francis Malléjac

Wakes are medium perturbations created by a moving object, such as wave patterns behind boats, or wingtip vortices following an aircraft. Here, we report about an experimental study of an uncharted form of parabolic wakes occurring in media with the group ...

American Physical Society (APS)2024

Experimental observation of topological transition in linear and nonlinear parametric oscillators

Romain Christophe Rémy Fleury, Benjamin Apffel

Parametric oscillators are examples of externally driven systems that can exhibit two stable states with opposite phase depending on the initial conditions. In this work, we propose to study what happens when the external forcing is perturbed by a continuo ...

2024