Spins in few-electron quantum dots

By Ronald Hanson, L. Kouwenhoven, Jason R. Petta, S. Tarucha, Lieven M. K. Vandersypen. 2006

2,087 citations recorded by the source corpus.

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.

Subfields: Atomic and Molecular Physics, and Optics, Computational Theory and Mathematics, Electrical and Electronic Engineering

View Paper: https://www.semanticscholar.org/paper/d763ae88aa15203291f83ef38353329894ee8f6c

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Citations in the corpus

Milestones toward Majorana-based quantum computing (2015, background): “1 and 2), which can then be readily measured via charge detection [58,59].”
Quantum Simulation Of The Quantum Rabi Model In A Trapped Ion (2017, background): “The JCM is an analytically solvable model that has been studied in cavity quantum electrodynamics [4–6], atomic physics [7], quantum dots [8], circuit quantum electrodynamics (cQED) [9,10], and trapped ions [11–14], among other quantum platforms.”
Continuous-time Monte Carlo methods for quantum impurity models (2010, background): “One important application of quantum impurity models is as representations of “single molecule” conductors and other nano-devices (Hanson et al., 2007).”
Optical Properties of Semiconductor Quantum Dots (2008, background): “In GaAs QDs the effective magnetic field due to the nuclei is a few mT, depending on the size of the dot, and evolves on a time scale that can be up to seconds [83].”
Nuclear spin physics in quantum dots: an optical investigation (2012, background): “A very high degree of control over carrier spin states and the mesoscopic nuclear spin system is also achieved in QDs defined by electrostatic potentials as summarized in the detailed review by Hanson et al. (2007).”
Quantum computers (2010, positive): “This latter process limits electron spin decoherence times ( T 2 ) to a few microseconds 43 .”
Engineered Open Systems and Quantum Simulations with Atoms and Ions (2012, background): “…et al., 2012; Häffner et al., 2008) and photons (O’Brien, 2007), but also solid state systems (Clarke and Wilhelm, 2008; Wrachtrup and Jelezko, 2006; Hanson et al., 2007), we will summarize below recent advances in these directions with a particular focus on engineered open many-body systems and…”
Interfacing single photons and single quantum dots with photonic nanostructures (2013, background): “In contrast, e.g., electrons confined in quantum dots may interact very strongly but this also makes the system vulnerable to decoherence processes from the environment and the interaction has limited spatial range (Hanson et al., 2007).”