Precession of entangled spin and pseudospin in double quantum dots

TL;DR

This paper explores the complex precession dynamics of entangled spin and pseudospin in double quantum dots, revealing new current resonances influenced by lead polarizations and their interplay with decoherence and pumping effects.

Contribution

It generalizes previous models to include arbitrary lead polarizations, uncovering richer resonance phenomena through combined spin-pseudospin precession analysis.

Findings

Identification of new current resonances due to entangled spin-pseudospin precession

Demonstration of the interplay between decoherence, pumping, and precession effects

Validation of results through numerical and analytical models

Abstract

Quantum dot spin valves are characterized by exchange fields which induce spin precession and generate current spin resonances even in absence of spin splitting. Analogous effects have been studied in double quantum dots, in which the orbital degree of freedom, the pseudospin, replaces the spin in the valve configuration. We generalize, now, this setup to allow for arbitrary spin and orbital polarization of the leads, thus obtaining an even richer variety of current resonances, stemming from the precession dynamics of entangled spin and pseudospin. We observe for both vectors a delicate interplay of decoherence, pumping and precession which can only be understood by also considering the dynamics of the spin-pseudospin correlators. The numerical results are obtained in the framework of a generalized master equation within the cotunneling approximation and are complemented by the analytics of a coherent sequential tunneling model.