Ultrafast manipulation of electron spins in a double quantum dot device: A real-time view

TL;DR

This paper presents a real-time analysis of ultrafast electron spin manipulation in a double quantum dot device with spin impurities, using advanced numerical simulations to optimize spin control and device performance.

Contribution

It introduces a novel real-time simulation method for spin dynamics in quantum dots with ultrafast pulses, enabling detailed understanding and engineering of spin responses.

Findings

Real-time spin dynamics captured during ultrafast voltage pulses.

Enhanced control of spin injection and read-out processes.

Validated approximate rate equations for electron spin behavior.

Abstract

We consider a double quantum dot system with two embedded and non-aligned spin impurities to manipulate the magnitude and polarization of the electron spin density. The device is attached to semi-infinite one-dimensional leads which are treated exactly. We provide a real-time description of the electron spin dynamics when a sequence of ultrafast voltage pulses acts on the device. The numerical simulations are carried out using a spin generalized and modified version of a recently proposed algorithm for the time propagation of open systems [Phys. Rev. B {\bf 72}, 035308 (2005)]. Time-dependent spin accumulations and spin currents are calculated during the entire operating regime which includes spin injection and read-out processes. The full knowledge of the electron dynamics allows us to engineer the transient responses and improve the device performance. An approximate rate equation for the electron spin is also derived and used to discuss the numerical results.