Interference and Switching of Josephson current carried by nonlocal spin-entangled electrons in a SQUID-like system with quantum dots

TL;DR

This paper explores a SQUID-like system with quantum dots that exhibits a unique magnetic-flux response in Josephson current due to nonlocal spin entanglement, enabling detection and control of split-tunneling phenomena.

Contribution

It introduces a novel Josephson current mechanism influenced by nonlocal spin entanglement, with a switchable feature for measuring split-tunneling currents.

Findings

The Josephson current period shifts from h/2e to h/e due to interference.

The device can detect the efficiency of Cooper-pair splitting.

A quantum switch for controlling the Josephson current is formulated.

Abstract

Josephson current of spin-entangled electrons through the two branches of a SQUID-like structure with two quantum dots exhibits a magnetic-flux response different from the conventional Josephson current. Due to their interference, the period of maximum Josephson current changes from $h/2e$ to $h/e$, which can be used for detecting the Cooper-pair splitting efficiency. The nonlocal spin entanglement provides a quantum mechanical functionale for switching on and off this novel Josephson current, and explicitly a switch is formulated by including a pilot junction. It is shown that the device can be used to measure the magnitude of split-tunneling Josephson current.