Scanning gate imaging of quantum dots in 1D ultra-thin InAs/InP nanowires

Boyd, Erin E.; Storm, Kristian; Samuelson, Lars; Westervelt, Robert

doi:10.1088/0957-4484/22/18/185201

Cited by 25 publications

(34 citation statements)

References 37 publications

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“…The conducting SPM tip acts as a moveable gate to capacitively probe the energy of electron states using Coulomb blockade spectroscopy by recording the conductance G as the tip is moved along the nanowire. [13][14][15][16]18 The geometry of the SPM tip potential and electron states in the sample are important for the proposed wavefunction imaging technique. The spatial width of the tip potential perturbation Φ tip (x-x tip ) created inside the nanowire is determined by the height of the tip above the nanowire axis.…”

Section: A Modelmentioning

confidence: 99%

“…4 The conducting tip of a cooled SPM has been used as a moveable gate to capacitively probe electrons inside nanostructures to image the flow of electron waves from a quantum point contact [5][6][7][8][9] and through a quantum ring [10][11][12] and to measure the energy of quantum states. [13][14][15][16][17][18] Semiconductor nanostructures are attractive for quantum devices. Few electron quantum dots made from GaAs/AlGaAs heterostructures that contain only a few electrons have welldefined quantum states that can be measured with Coulomb blockade spectroscopy 19,20 and coupled quantum dots can be used for quantum information processing.…”

Section: Introductionmentioning

confidence: 99%

“…[23][24][25][26] A very narrow nanowire can line up electrons into a single row, to form a one-dimensional (1D) electron gas. 18 A major challenge for developers of quantum devices is to obtain information about the electronic wavefunction of quantum states in the interior of devices. Suggested techniques include a grown-in potential perturbation, 27 changing the phase with the vector potential of an applied magnetic field, 28 and a potential perturbation from an external probe.…”

Section: Introductionmentioning

confidence: 99%

“…The nanostructure chosen to illustrate the imaging techniques is a long InAs quantum dot formed by two tunnel barriers along an otherwise uniform nanowire. 18,24,25 With a suitably narrow nanowire, only the lowest subband is occupied and the electrons form a 1D system. Figure 1 shows a schematic diagram of the SPM setup, including the nanowire with source and drain contacts, a SiO 2 insulating layer, and a conducting backgate.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Extracting the density profile of an electronic wave function in a quantum dot

Boyd

Westervelt

2011

Phys. Rev. B

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The Harvard community has made this article openly available. Please share how this access benefits you. Your story matters Coulomb blockade spectroscopy. When the tip is close to the nanowire dot, it dents the wavefunction Ψ(x) of the quantum state, changing the electron's energy by an amount proportional to |Ψ(x)| 2 . By recording the change in energy as the SPM tip is moved along the length of the dot, the density profile of the electronic wavefunction can be found along the length of the quantum dot.2

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Section: A Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Extracting the density profile of an electronic wave function in a quantum dot

Boyd

Westervelt

2011

Phys. Rev. B

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“…The study covers up to four electrons and quantum dots of various symmetries and profiles. We discuss the adequacy of the perturbative approach for extraction of the electron density [6,11,12] confined in quantum dots and the fidelity of charge images outside the perturbative regime. We find that the images obtained with repulsive (attractive) tip potential tend to overestimate (underestimate) the electron localization.…”

Section: Introductionmentioning

confidence: 99%

Charge density mapping of strongly-correlated few-electron two-dimensional quantum dots by the scanning probe technique

Wach

Żebrowski²,

Szafran³

2013

J. Phys.: Condens. Matter

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Abstract. We perform a numerical simulation of mapping of charge confined in quantum dots by the scanning probe technique. We solve the few-electron Schrödinger equation with the exact diagonalization approach and evaluate the energy maps in function of the probe position. Next, from the energy maps we try to reproduce the charge density distribution using an integral equation given by the perturbation theory. The reproduced density maps are confronted with the original ones. The present study covers two-dimensional quantum dots of various geometries and profiles with the one-dimensional (1D) quantum dot as a limit case. We concentrate on large quantum dots for which strong electron-electron correlations appear. For circular dots the correlations lead to formation of Wigner molecules that in the presence of the tip appear in the laboratory frame. The unperturbed rotationally-symmetric charge density is surprisingly well reproduced by the mapping. We find in general that the size of the confined droplet as well as the spatial extent of the charge density maxima is underestimated for repulsive tip potential and overestimated for the attractive tip. In lower-symmetry quantum dots the Wigner molecules with single-electron islands nucleate for some electron numbers even in the absence of the tip. These charge densities are well resolved by the mapping. The single-electron islands appear in the laboratory frame provided that classical point charge density distribution is unique, in the 1D limit of confinement in particular. We demonstrate that for electron systems which possess a few equivalent classical configurations the repulsive probe switches between the configurations. In consequence the charge density evades mapping by the repulsive probe.

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Probe‐assisted spin manipulation in one‐dimensional quantum dots

Gindikin

Sablikov

2015

Physica Rapid Research Ltrs

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We study a spin structure that arises in a one-dimensional quantum dot with zero total spin under the action of a charged tip of a scanning probe microscope in the presence of a weak magnetic field. The evolution of the spin structure with changing the probe position is traced to show that the movable probe can be an effective tool to manipulate the spin. The spin structures are formed when the probe is located in certain regions along the dot due to the Coulomb interaction of electrons as they are redistributed between the two sections in which the quantum dot is divided by the potential barrier created by the probe. There are two main states: spin-polarized and non-polarized ones. The transition between them is accompanied by a spin precession governed by the Rashba spin-orbit interaction induced by the electric field of the probe. In the transition region the spin density changes strongly while the charge distribution remains nearly unchanged.Comment: 6 pages, 6 figures. Numerical data illustrating the spin manipulation effect are essentially updated. This version is published online in Physica Status Solidi (RRL) - Rapid Research Letter

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Scanning gate imaging of quantum dots in 1D ultra-thin InAs/InP nanowires

Cited by 25 publications

References 37 publications

Extracting the density profile of an electronic wave function in a quantum dot

Extracting the density profile of an electronic wave function in a quantum dot

Charge density mapping of strongly-correlated few-electron two-dimensional quantum dots by the scanning probe technique

Probe‐assisted spin manipulation in one‐dimensional quantum dots

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