Theoretical study of electronic states and spin operation in coupled quantum dots

D. Goto, M. Eto

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

We theoretically study the electronic states and spin operation in coupled quantum dots, based on the calculations of many-body wavefunctions. We adopt a tight-binding model on a square lattice with a smooth tunnel barrier around its center. Taking into account the electron-electron interaction by the exact diagonalization method, we evaluate the spin coupling J between two electron spins, as a function of magnetic field perpendicular to the quantum dots, and show a transition from antiferromagnetic coupling (J > 0) to ferromagnetic coupling (J < 0). The coupling J is not seriously influenced by the size difference between the dots if the energy levels are tuned to match each other using the gate voltage. Next, we simulate SWAP gate operation by calculating the time development of two electron spins. A nonadiabatic change of the tunnel barrier between the quantum dots may cause operation errors, due to the contribution from high energy states. The complete exchange of the spin states could be also blocked by the spin-orbit interaction.

Original languageEnglish
Title of host publicationMS+S 2006 - Controllable Quantum States
Subtitle of host publicationMesoscopic Superconductivity and Spintronics, Proceedings of the International Symposium
PublisherWorld Scientific Publishing Co. Pte Ltd
Pages239-244
Number of pages6
ISBN (Print)9812814612, 9789812814616
Publication statusPublished - 2008 Jan 1
Event4th International Symposium on Mesoscopic Superconductivity and Spintronics, MS+S 2006 - Atsugi, Japan
Duration: 2006 Feb 272006 Mar 2

Publication series

NameMS+S 2006 - Controllable Quantum States: Mesoscopic Superconductivity and Spintronics, Proceedings of the International Symposium

Other

Other4th International Symposium on Mesoscopic Superconductivity and Spintronics, MS+S 2006
CountryJapan
CityAtsugi
Period06/2/2706/3/2

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ASJC Scopus subject areas

  • Electrical and Electronic Engineering

Cite this

Goto, D., & Eto, M. (2008). Theoretical study of electronic states and spin operation in coupled quantum dots. In MS+S 2006 - Controllable Quantum States: Mesoscopic Superconductivity and Spintronics, Proceedings of the International Symposium (pp. 239-244). (MS+S 2006 - Controllable Quantum States: Mesoscopic Superconductivity and Spintronics, Proceedings of the International Symposium). World Scientific Publishing Co. Pte Ltd.