Enhancement of Cooper pair splitting by multiple scattering

TL;DR

This paper investigates how additional barriers affect nonlocal conductance and Cooper pair splitting in three-terminal NSN structures, finding that reflectionless tunneling does not enhance splitting, but Fabry-Perot resonances in ballistic systems can selectively boost crossed Andreev processes.

Contribution

It demonstrates that reflectionless tunneling does not improve Cooper pair splitting, while Fabry-Perot resonances in ballistic systems can be used to enhance specific nonlocal processes.

Findings

Reflectionless tunneling does not enhance nonlocal conductance or pair splitting.

Fabry-Perot resonances enable selective enhancement of crossed Andreev processes.

Tuning system parameters can control contributions to conductance and correlations.

Abstract

In three-terminal NSN hybrid structures the influence of additional barriers on the nonlocal conductance and on current cross-correlations is studied within a scattering theory. In metallic systems with additional barriers and phase averaging, which simulate disordered regions, local processes can be enhanced by reflectionless tunneling but this mechanism has little influence on nonlocal processes and on current cross-correlations. Therefore Cooper pair splitting cannot be enhanced by reflectionless tunneling. On the contrary, in ballistic systems, additional barriers lead to Fabry-Perot resonances and allow to separate the different contributions to the conductance and to the current cross-correlations. In particular, crossed Andreev processes can be selectively enhanced by tuning the length or the chemical potential of the interbarrier region.