Coulomb charging effects in an open quantum dot device

Ткаченко, О. А.; Ткаченко, В. А.; Baksheyev, D. G.; Liang, Chi‐Te; Simmons, M. Y.; Smith, Charles G.; Ritchie, D. A.; Kim, Gil‐Ho; Pepper, M.

doi:10.1088/0953-8984/13/42/312

Cited by 15 publications

(17 citation statements)

References 28 publications

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“…Charging effects are generally found to diminish as the contacts' conductances are increased [10][11][12][13][14][15][16][17][18] . However, while some measurements support the fundamental prediction 6-8 that charge quantization vanishes in the presence of one ballistic channel [10][11][12]17 , others conclude the opposite [18][19][20][21][22][23] . Unsurprisingly, the scaling behavior predicted for the reduction of charge quantization [6][7][8] has also remained, up to now, elusive despite several attempts 16,17 .…”

mentioning

confidence: 99%

Controlling charge quantization with quantum fluctuations

Jezouin

Iftikhar

Anthore

et al. 2016

Nature

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In 1909, Millikan showed that the charge of electrically isolated systems is quantized in units of the elementary electron charge e. Today, the persistence of charge quantization in small, weakly connected conductors allows for circuits in which single electrons are manipulated, with applications in, for example, metrology, detectors and thermometry. However, as the connection strength is increased, the discreteness of charge is progressively reduced by quantum fluctuations. Here we report the full quantum control and characterization of charge quantization. By using semiconductor-based tunable elemental conduction channels to connect a micrometre-scale metallic island to a circuit, we explore the complete evolution of charge quantization while scanning the entire range of connection strengths, from a very weak (tunnel) to a perfect (ballistic) contact. We observe, when approaching the ballistic limit, that charge quantization is destroyed by quantum fluctuations, and scales as the square root of the residual probability for an electron to be reflected across the quantum channel; this scaling also applies beyond the different regimes of connection strength currently accessible to theory. At increased temperatures, the thermal fluctuations result in an exponential suppression of charge quantization and in a universal square-root scaling, valid for all connection strengths, in agreement with expectations. Besides being pertinent for the improvement of single-electron circuits and their applications, and for the metal-semiconductor hybrids relevant to topological quantum computing, knowledge of the quantum laws of electricity will be essential for the quantum engineering of future nanoelectronic devices.

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confidence: 99%

Controlling charge quantization with quantum fluctuations

Jezouin

Iftikhar

Anthore

et al. 2016

Nature

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“…Coulomb charging is required in order for the Kondo effect to be observed in quantum dots; this is usually observed in a system having low dot-electrode transmission probabilities and conductance less than 2e 2 / h . However, Coulomb charging effects have often been observed in open quantum dots where 2 e 2 / h < G < 6 e 2 / h 38 39 40 . Therefore, high overall conductance values of 3e 2 / h < G < 5e 2 / h does not necessarily exclude the possibility of Coulomb charging and the Kondo effect in our open quantum dot device.…”

Section: Discussionmentioning

confidence: 99%

Kondo-like zero-bias conductance anomaly in a three-dimensional topological insulator nanowire

Cho

Zhong

Schneeloch

et al. 2016

Sci Rep

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Zero-bias anomalies in topological nanowires have recently captured significant attention, as they are possible signatures of Majorana modes. Yet there are many other possible origins of zero-bias peaks in nanowires—for example, weak localization, Andreev bound states, or the Kondo effect. Here, we discuss observations of differential-conductance peaks at zero-bias voltage in non-superconducting electronic transport through a 3D topological insulator (Bi1.33Sb0.67)Se3 nanowire. The zero-bias conductance peaks show logarithmic temperature dependence and often linear splitting with magnetic fields, both of which are signatures of the Kondo effect in quantum dots. We characterize the zero-bias peaks and discuss their origin.

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“…The other is the open quantum dot with a size of approx. 0.7 µm created at the Cavendish Laboratory, UK, using a three-layered system of submicron and ultrathin (60 nm) metallic gates [10][11][12][13][14]. To create these devices the ISP SB RAS and the Cavendish Laboratory have improved the parameters of GaAs/AlGaAs heterostructure molecular beam epitaxy process and obtained 2D electron gas with a low-temperature mobility of 0.5 × 10 6 and 2.5 × 10 6 cm 2 /(V × s), respectively.…”

Section: Introductionmentioning

confidence: 99%

“…Comparatively large dimensions of these devices (0.7 µm) combined with the high quality of the 2D electron gas and nanolithography allowed ignoring the disorder in the first approximation. The self-consistent solution of the 3D electrostatics problem provided for close-to-real simple forms of effective 2D potential U(x,y) that can be used for calculating the conductance of the devices in a zero magnetic field [7,[12][13][14]. The calculated potential U(x,y) for these structures is symmetrical relative to the lines x = 0 and y = 0 (see figs 1, 2 [7], fig.…”

Section: Introductionmentioning

confidence: 99%

Aharonov–Bohm oscillations and equilibrium current distributions in open quantum dot and in ring interferometer

Ткаченко¹,

Baksheev²,

Ткаченко³

2020

MoEM

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Magnetotransport in two submicron-sized devices formed on the basis of GaAs/AlGaAs structures has been simulated using nonequilibrium Green functions. The effect of a perpendicular magnetic field on quantum transport in a quasi-one-dimensional quantum dot and in an Aharonov–Bohm interferometer has been analyzed in a single-particle approximation. Magnetic field oscillations of two-terminal conductance of the devices, equilibrium (persistent) current distributions and magnetic moment generated in the devices by persistent currents have been determined using numerical methods. Correlations between the magnetic moment, magnetic field oscillations of conductance and energy resonance in a specific magnetic field have been traced. Sufficiently regular conductance oscillations similar to Aharonov–Bohm ones have been revealed for a quasi-one-dimensional quantum dot at small magnetic fields (0.05–0.4 T). For a ring interferometer the contribution to the total equilibrium current and magnetic moment at a specific energy may change abruptly both in magnitude and in sign as a result of changing magnetic field within one Aharonov–Bohm oscillation. We show that the conductance of an interferometer is determined not by the number of modes propagating in the ring but rather by the effect of triangular quantum dots at the ring entrance that produce a strong reflection. The period of the calculated Aharonov–Bohm oscillations is in agreement with the measurement results for these devices.

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Coulomb charging effects in an open quantum dot device

Cited by 15 publications

References 28 publications

Controlling charge quantization with quantum fluctuations

Controlling charge quantization with quantum fluctuations

Kondo-like zero-bias conductance anomaly in a three-dimensional topological insulator nanowire

Aharonov–Bohm oscillations and equilibrium current distributions in open quantum dot and in ring interferometer

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