Strong nonlocal tuning of the current-phase relation of a quantum dot based Andreev molecule

Abstract

Multiple systems hosting Andreev molecular states have been proposed and studied, consisting of closely spaced Josephson junctions modeled as ballistic channels. We show that replacing the ballistic channels in the weak link of the Josephson junctions with quantum dots (QD), leads to a very exciting, rich phase diagram. It shows a strong nonlocal Josephson effect: as one junction is tuned the current-phase relation of the other junction is modified. This architecture hosts $0 - \pi$ transitions and shows a tunable anomalous phase-shift $\phi_0$ , nonlocally controlled in both cases, without relying on spin-orbit interaction or Zeeman fields. In addition significant superconducting diode effect can also be observed. The presented non-local current-phase relation can be used as a signature of the formation of an Andreev molecular state, as well as to introduce new ways to tune quantum architectures.