Spins in few-electron quantum dots

R. Hanson, L. P. Kouwenhoven, J. R. Petta, S. Tarucha, and L. M. K. Vandersypen
Rev. Mod. Phys. 79, 1217 – Published 1 October 2007

Abstract

The canonical example of a quantum-mechanical two-level system is spin. The simplest picture of spin is a magnetic moment pointing up or down. The full quantum properties of spin become apparent in phenomena such as superpositions of spin states, entanglement among spins, and quantum measurements. Many of these phenomena have been observed in experiments performed on ensembles of particles with spin. Only in recent years have systems been realized in which individual electrons can be trapped and their quantum properties can be studied, thus avoiding unnecessary ensemble averaging. This review describes experiments performed with quantum dots, which are nanometer-scale boxes defined in a semiconductor host material. Quantum dots can hold a precise but tunable number of electron spins starting with 0, 1, 2, etc. Electrical contacts can be made for charge transport measurements and electrostatic gates can be used for controlling the dot potential. This system provides virtually full control over individual electrons. This new, enabling technology is stimulating research on individual spins. This review describes the physics of spins in quantum dots containing one or two electrons, from an experimentalist’s viewpoint. Various methods for extracting spin properties from experiment are presented, restricted exclusively to electrical measurements. Furthermore, experimental techniques are discussed that allow for (1) the rotation of an electron spin into a superposition of up and down, (2) the measurement of the quantum state of an individual spin, and (3) the control of the interaction between two neighboring spins by the Heisenberg exchange interaction. Finally, the physics of the relevant relaxation and dephasing mechanisms is reviewed and experimental results are compared with theories for spin-orbit and hyperfine interactions. All these subjects are directly relevant for the fields of quantum information processing and spintronics with single spins (i.e., single spintronics).

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  • Publisher error corrected 4 October 2007

DOI:https://doi.org/10.1103/RevModPhys.79.1217

©2007 American Physical Society

Corrections

4 October 2007

Erratum

Publisher's Note: Spins in few-electron quantum dots [Rev. Mod. Phys. 79, 1217 (2007)]

R. Hanson, L. P. Kouwenhoven, J. R. Petta, S. Tarucha, and L. M. K. Vandersypen
Rev. Mod. Phys. 79, 1455 (2007)

Authors & Affiliations

R. Hanson*

  • Center for Spintronics and Quantum Computation, University of California, Santa Barbara, California 93106, USA and Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands

L. P. Kouwenhoven

  • Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands

J. R. Petta

  • Department of Physics, Princeton University, Princeton, New Jersey 08544, USA and Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA

S. Tarucha

  • Department of Applied Physics and ICORP-JST, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-8656, Japan

L. M. K. Vandersypen

  • Kavli Institute of NanoScience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft, The Netherlands

  • *Electronic address: hanson@physics.ucsb.edu

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Issue

Vol. 79, Iss. 4 — October - December 2007

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