Laterally coupled self-assembled InAs quantum dots embedded in resonant tunnel diode with multigate electrodes

Amaha, S.; Hatano, T.; Teraoka, S.; Shibatomi, A.; Tarucha, Seigo; Nakata, Yoshihiro; Miyazawa, T.; Oshima, Takeshi; Usuki, Tatsuya; Yokoyama, Naoki

doi:10.1063/1.2920205

Cited by 38 publications

(27 citation statements)

References 29 publications

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“…It is instrumentally challenging to study self-assembled QDs via conventional transport and charge sensing methods because of the difficulty in attaching electrodes. Although progress is being made (8)(9)(10)(11)(12), these techniques have very small yield and therefore make it difficult to assess variation in QD electronic properties. Compared to typical QDs studied via transport measurements, in particular lithographically defined QDs, self-assembled QDs can be fabricated to have smaller sizes, stronger confinement potentials, and a more scalable fabrication process, all of which make them attractive for practical applications.…”

mentioning

confidence: 99%

Energy levels of few-electron quantum dots imaged and characterized by atomic force microscopy

Cockins

Miyahara

Bennett

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

119

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Strong confinement of charges in few-electron systems such as in atoms, molecules, and quantum dots leads to a spectrum of discrete energy levels often shared by several degenerate states. Because the electronic structure is key to understanding their chemical properties, methods that probe these energy levels in situ are important. We show how electrostatic force detection using atomic force microscopy reveals the electronic structure of individual and coupled self-assembled quantum dots. An electron addition spectrum results from a change in cantilever resonance frequency and dissipation when an electron tunnels on/off a dot. The spectra show clear level degeneracies in isolated quantum dots, supported by the quantitative measurement of predicted temperature-dependent shifts of Coulomb blockade peaks. Scanning the surface shows that several quantum dots may reside on what topographically appears to be just one. Relative coupling strengths can be estimated from these images of grouped coupled dots.nanoelectronics | single-electron charging | shell structure | electrostatic force microscopy T he ability to confine single charges at discrete energy levels makes semiconductor quantum dots (QDs) promising candidates as a platform for quantum computation (1, 2) and singlephoton sources (3). Tremendous progress has been made not only in understanding the properties of single electrons in QDs but also in controlling their quantum states, which is an essential prerequisite for quantum computation (4). Single-electron transport measurements have been the main experimental technique for investigating electron tunneling into QDs (5). Charge sensing techniques using built-in charge sensors, such as quantum point contacts (6), complement transport measurements because lower electron tunneling rates can be monitored with even real-time detection being possible (7). It is instrumentally challenging to study self-assembled QDs via conventional transport and charge sensing methods because of the difficulty in attaching electrodes. Although progress is being made (8-12), these techniques have very small yield and therefore make it difficult to assess variation in QD electronic properties. Compared to typical QDs studied via transport measurements, in particular lithographically defined QDs, self-assembled QDs can be fabricated to have smaller sizes, stronger confinement potentials, and a more scalable fabrication process, all of which make them attractive for practical applications.In this paper, we focus on an alternative technique for studying QDs that is better suited for self-assembled QDs: charge sensing by atomic force microscopy (AFM). Charge sensing by AFM is a convenient method to study the electronic structure of QDs because nanoelectrodes are not required and large numbers of QDs can be investigated in one experiment. Termed single-electron electrostatic force microscopy (e-EFM), this technique relies on the high force sensitivity of AFM to detect the electrostatic force resulting from single electrons tunneling into ...

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mentioning

confidence: 99%

Energy levels of few-electron quantum dots imaged and characterized by atomic force microscopy

Cockins

Miyahara

Bennett

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

119

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“…38) The recent development of a fabrication technique has stimulated theoretical investigations of various TTQD Kondo systems because of the high potentiality for versatile quantum devices. [39][40][41][42][43][44][45][46][47][48][49][50][51] The tunable parameters in the TTQD are interdot electron-hopping matrix elements and intradot orbital energy levels used as a standard theoretical setup.…”

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confidence: 99%

Antisymmetric Spin–Orbit Coupling Effect on Kondo-Induced Electric Polarization in a Triangular Triple Quantum Dot

2017

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We study the local antisymmetric spin-orbit (ASO) coupling effect on spin, orbital, and charge degrees of freedom for the Kondo effect in a triangular triple quantum dot (TTQD). Here, one of the three QDs is coupled to a metallic lead through electron tunneling, and a local electric polarization is induced by the Kondo effect. The ASO interaction is introduced in the other two coupled QDs on the opposite side of the lead. Generally, the ASO coupling effect is very weak and not easily detectable, but it essentially causes spin and charge reconfigurations in the TTQD through the Kondo effect. Using an extended Anderson model for the TTQD Kondo system, we elucidate that the ASO coupling gives rise to a considerable reduction of the emergent electric polarization, as a consequence of the parity mixing of molecular orbitals in the triangular loop as well as the spin-up and spin-down coupling of local electrons. The latter leads to a local diamagnetic susceptibility owing to the ASO coupled spins. We also show that the Kondo-induced electric polarization can be controlled by the ASO coupling as well as by the magnetic flux penetrating through the TTQD.

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“…In this paper we report measurements from a design which creates few electron triple quantum dots in series. Several other groups have recently reported preliminary measurements on triple quantum dot devices [10,11,12,13,14]. Few electron triple quantum dot circuits should not be regarded as a stepping stone to a larger system one qubit at a time, but as a device where important concepts can be demonstrated, such as spin buses [15] and entanglement [16] which will certainly be required in more complex architectures for running useful quantum algorithms.…”

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confidence: 99%

A tunable few electron triple quantum dot

Gaudreau¹,

Kam²,

Granger³

et al. 2009

Applied Physics Letters

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In this paper we report on a tuneable few electron lateral triple quantum dot design. The quantum dot potentials are arranged in series. The device is aimed at studies of triple quantum dot properties where knowing the exact number of electrons is important as well as quantum information applications involving electron spin qubits. We demonstrate tuning strategies for achieving required resonant conditions such as quadruple points where all three quantum dots are on resonance. We find that in such a device resonant conditions at specific configurations are accompanied by novel charge transfer behaviour.

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Laterally coupled self-assembled InAs quantum dots embedded in resonant tunnel diode with multigate electrodes

Cited by 38 publications

References 29 publications

Energy levels of few-electron quantum dots imaged and characterized by atomic force microscopy

Energy levels of few-electron quantum dots imaged and characterized by atomic force microscopy

Antisymmetric Spin–Orbit Coupling Effect on Kondo-Induced Electric Polarization in a Triangular Triple Quantum Dot

A tunable few electron triple quantum dot

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