Detecting entanglement using a double quantum dot turnstile

TL;DR

This paper proposes a practical scheme using a double quantum dot to detect and produce entangled electron pairs on demand, utilizing time-dependent controls and spin measurements.

Contribution

It introduces a novel experimental setup for detecting electron spin entanglement with current technology, combining quantum dots, gate control, and spin-polarized detection.

Findings

Coherent evolution of entangled spins can be monitored via coincidence counting.

The setup enables on-demand production of entangled electron pairs.

The proposed method is feasible with existing experimental techniques.

Abstract

We propose a scheme based on using the singlet ground state of an electron spin pair in a double quantum dot nanostructure as a suitable set-up for detecting entanglement between electron spins via the measurement of an optimal entanglement witness. Using time-dependent gate voltages and magnetic fields the entangled spins are separated and coherently rotated in the quantum dots and subsequently detected at spin-polarized quantum point contacts. We analyze the coherent time evolution of the entangled pair and show that by counting coincidences in the four exits an entanglement test can be done. This set-up is close to present-day experimental possibilities and can be used to produce pairs of entangled electrons ``on demand''.