Tunable interdot coupling via Andreev levels

Quantum dot-superconductor-quantum dot is a widely used mesoscopic system for studying fundamental physics, such as Cooper pair splitting, spin qubit coupling via superconductor among others. However, when the superconductor is of metallic nature, the interdot tunneling strength decays with $k_F L$ in a power law and is difficult to fine-tune by system parameters. In this work we consider a short semiconductor-superconductor hybrid nanowire for which the low-energy physics is a pair of Andreev levels. We find that the Andreev-level-mediated interdot tunneling strength is tunable and has a universal dependence on the nanowire parameters, such as chemical potential, spin-orbit interaction and induced Zeeman spin splitting. Moreover, we show that in tunnel spectroscopy resonant current flowing through the system is proportional to the square of interdot tunneling strength when dots are connected to external normal leads. Our findings will facilitate the device characterization and optimization in related experiments.