Real-time observation of charge-spin cooperative dynamics driven by a nonequilibrium phonon environment

TL;DR

This paper reports the experimental observation of charge-spin dynamics in a quantum dot system driven by a non-equilibrium phonon environment, revealing phonon-induced spin-flip enhancements and directional spin state accumulation.

Contribution

It demonstrates how a non-equilibrium phonon environment influences charge-spin dynamics in quantum dots, a novel insight into thermodynamic processes at the nanoscale.

Findings

Enhanced spin-flip processes due to phonon excitation and spin-orbit interaction

Directional dependence of spin-flip rates caused by phonon density gradients

Accumulation of parallel spin states in the double quantum dot system

Abstract

Quantum dots are recognized as a suitable platform for studying thermodynamic phenomena involving single electronic charges and spins in nano-scale devices. However, such a thermodynamic system is usually driven by electron reservoirs at different temperatures, not by a lattice temperature gradient. We report on experimental observations of charge-spin cooperative dynamics in transitions of two-electron spin states in a GaAs double quantum dot located in a non-equilibrium phonon environment. Enhancements in the spin-flip processes are observed, originating from phonon excitation combined with the spin-orbit interaction. In addition, due to the spatial gradient of phonon density between the dots, the spin-flip rate during an inter-dot electron tunnel from a hot to a cold dot is more enhanced than in the other direction, resulting in accumulation of parallel spin states in the double dot.