Nanoscale spin rectifiers controlled by the Stark effect

TL;DR

This paper demonstrates a scalable method to control double quantum dots using the Stark effect, enabling spin blockade detection at higher temperatures and revealing new magnetic field effects.

Contribution

It introduces a Stark effect-based control technique for DQDs that does not require nanometer-scale local gates, allowing scalable quantum device operation.

Findings

Spin blockade observed up to 10 K in InAs/InP nanowire DQDs

Independent addressing of dots 5 nm apart via Stark effect

Re-entrant spin blockade lifting with magnetic field

Abstract

The control of orbital and spin state of single electrons is a key ingredient for quantum information processing, novel detection schemes, and, more generally, is of much relevance for spintronics. Coulomb and spin blockade (SB) in double quantum dots (DQDs) enable advanced single-spin operations that would be available even for room-temperature applications for sufficiently small devices. To date, however, spin operations in DQDs were observed at sub-Kelvin temperatures, a key reason being that scaling a DQD system while retaining an independent field-effect control on the individual dots is very challenging. Here we show that quantum-confined Stark effect allows an independent addressing of two dots only 5 nm apart with no need for aligned nanometer-size local gating. We thus demonstrate a scalable method to fully control a DQD device, regardless of its physical size. In the present implementation we show InAs/InP nanowire (NW) DQDs that display an experimentally detectable SB up to 10 K. We also report and discuss an unexpected re-entrant SB lifting as a function magnetic-field intensity.