Finite bias Cooper pair splitting

TL;DR

This paper investigates how a finite potential difference affects conductance in a Cooper pair splitter with quantum dots, demonstrating tunable dominance between Cooper pair splitting and elastic co-tunneling.

Contribution

It introduces bias-dependent spectroscopy to control and understand transport mechanisms in Cooper pair splitters using InAs nanowire devices.

Findings

Electrical transport can be tuned to favor CPS or EC.

Finite bias influences the energy-dependent density of states.

Bias-dependent spectroscopy enhances understanding of CPS devices.

Abstract

In a device with a superconductor coupled to two parallel quantum dots (QDs) the electrical tunability of the QD levels can be used to exploit non-classical current correlations due to the splitting of Cooper pairs. We experimentally investigate the effect of a finite potential difference across one quantum dot on the conductance through the other completely grounded QD in a Cooper pair splitter fabricated on an InAs nanowire. We demonstrate that the electrical transport through the device can be tuned by electrical means to be dominated either by Cooper pair splitting (CPS), or by elastic co-tunneling (EC). The basic experimental findings can be understood by considering the energy dependent density of states in a QD. The reported experiments add bias-dependent spectroscopy to the investigative tools necessary to develop CPS-based sources of entangled electrons in solid-state devices.