Electric field tunable exchange interaction in InAs/GaAs coupled quantum dots

TL;DR

This paper demonstrates how applying an electric field can tune the exchange interaction in InAs/GaAs coupled quantum dots, enabling potential control of spin states for quantum information processing.

Contribution

It introduces a method to control exchange interactions in coupled quantum dots through electric field tuning, observed via polarization-dependent photoluminescence spectra.

Findings

Electric field induces resonance between hole energy levels.

Anticrossings observed in spectra indicate molecular orbital formation.

Polarization memory varies with electric field, showing exchange interaction control.

Abstract

Spin manipulation in coupled quantum dots is of interest for quantum information applications. Control of the exchange interaction between electrons and holes via an applied electric field may provide a promising technique for such spin control. Polarization dependent photoluminescence (PL) spectra were used to investigate the spin dependent interactions in coupled quantum dot systems and by varying an electric field, the ground state hole energy levels are brought into resonance, resulting in the formation of molecular orbitals observed as anticrossings between the direct and indirect transitions in the spectra. The indirect and direct transitions of the neutral exciton demonstrate high and low circular polarization memory respectively due to variation in the exchange interaction. The ratio between the polarization values as a function of electric field, and the barrier height was measured. These results indicate a possible method of tuning between indirect and direct configurations to control the degree of exchange interaction.