Attraction between electrons in a metallic dot capacitively coupled to a superconducting island

Cecilia Holmqvist (1, 2) , Denis Feinberg (3) , Alex Zazunov (4, 5)

1 NEEL - Institut Néel
2 Applied Quantum Physics Laboratory, MC2
3 NEEL - ThQC - Théorie Quantique des Circuits
4 LPM2C - Laboratoire de physique et modélisation des milieux condensés
5 CPT - Centre de Physique Théorique - UMR 6207

We consider the hybrid set-up formed by a metallic dot, capacitively coupled to a superconducting island S connected to a bulk superconductor by a Josephson junction. Charge fluctuations in S act as a dynamical gate and screen the electronic repulsion in the metallic dot, yielding instead a net attraction. As the offset charge of the metallic dot is increased, positive steps ($+2e$) skipping charge numbers appear, followed by negative ones ($-e$) signaling the occurrence of a negative differential capacitance. A circuit set-up with a detection scheme is proposed, as well as potential applications in nanoelectronics.

Mots clés: nanostructures; superconductivity; Coulomb blockade

Domaines: Systèmes mésoscopiques et effet Hall quantique [cond-mat.mes-hall]

Cecilia Holmqvist, Denis Feinberg, Alex Zazunov. Attraction between electrons in a metallic dot capacitively coupled to a superconducting island. 2007. ⟨hal-00136840v3⟩