Multistability and spin diffusion enhanced lifetimes in dynamic nuclear polarization in a double quantum dot

TL;DR

This paper demonstrates how dynamic nuclear spin polarization combined with electric-dipole-induced spin resonance in a double quantum dot can reveal multiple stable states and enhance nuclear spin lifetimes through diffusion, advancing quantum information prospects.

Contribution

It introduces a novel experimental approach combining DNP and EDSR in a double quantum dot with nanomagnets, revealing multistability and stabilization mechanisms of nuclear spins.

Findings

Identification of multiple fixed points in nuclear spin polarization.

Nuclear spin diffusion significantly stabilizes nuclear spins.

Direct access to nuclear polarization distribution in quantum dots.

Abstract

The control of nuclear spins in quantum dots is essential to explore their many-body dynamics and exploit their prospects for quantum information processing. We present a unique combination of dynamic nuclear spin polarization and electric-dipole-induced spin resonance in an electrostatically defined double quantum dot (DQD) exposed to the strongly inhomogeneous field of two on-chip nanomagnets. Our experiments provide direct and unrivaled access to the nuclear spin polarization distribution and allow us to establish and characterize multiple fixed points. Further, we demonstrate polarization of the DQD environment by nuclear spin diffusion which significantly stabilizes the nuclear spins inside the DQD.