Lab::Measurement—A portable and extensible framework for controlling lab equipment and conducting measurements

Low‐temperature transport spectroscopy measurements on a quantum dot lithographically defined in a multiwall MoS2 nanotube are demonstrated. At T = 300 mK, clear Coulomb blockade is observed, with charging energies in the range of 1 meV. In single‐electron tunneling, discrete conductance resonances are visible at finite bias. Additionally, a magnetic field perpendicular to the nanotube axis reveals clear indications of quantum state transitions, with effective g factors consistent with published theoretical predictions.

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“…Strunk and D. Weiss for the use of experimental facilities. The data have been recorded using the Lab:Measurement software package …”

Section: Acknowledgementsmentioning

confidence: 99%

Coulomb Blockade Spectroscopy of a MoS₂ Nanotube

Reinhardt

Pirker

Bäuml

et al. 2019

Physica Rapid Research Ltrs

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“…We also thank S. Ilani for stimulating discussions. The measurement data has been recorded using the Lab::Measurement software package [31].…”

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confidence: 99%

Shaping Electron Wave Functions in a Carbon Nanotube with a Parallel Magnetic Field

et al. 2019

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A magnetic field, through its vector potential, usually causes measurable changes in the electron wave function only in the direction transverse to the field. Here we demonstrate experimentally and theoretically that in carbon nanotube quantum dots, combining cylindrical topology and bipartite hexagonal lattice, a magnetic field along the nanotube axis impacts also the longitudinal profile of the electronic states. With the high (up to 17 T) magnetic fields in our experiment the wave functions can be tuned all the way from "half-wave resonator" shape, with nodes at both ends, to "quarter-wave resonator" shape, with an antinode at one end. This in turn causes a distinct dependence of the conductance on the magnetic field. Our results demonstrate a new strategy for the control of wave functions using magnetic fields in quantum systems with nontrivial lattice and topology.As first noticed by Aharonov and Bohm [1], when a charged quantum particle travels in a finite electromagnetic potential, its wave function acquires a phase whose magnitude depends on the travelled path. For particles with electric charge q moving along a closed path, the phase shift ϕ AB = qΦ B /h, known as Aharonov-Bohm shift, is expressed in terms of the magnetic flux Φ B across the enclosed area. Because Φ B depends only on the magnitude of the magnetic field component normal to this area's surface, the phase is acquired along directions transverse to the magnetic field, see Fig. 1(a). In mesoscopic rings or tubular structures pierced by a magnetic field, the phase changes the quantization condition for the tangential part of the electronic wave vector by k ⊥ → k ⊥ + ϕ AB /r (with r the radius of the ring or tubulus) and is at the basis of remarkable quantum interference phenomena [2]. However, as the perpendicular components of the magnetic vector potential commute with the parallel component of the momentum, a parallel magnetic field is not expected to affect the wave function along the field.Also in carbon nanotubes (CNTs), the electronic wave function acquires an Aharonov-Bohm phase when a magnetic field is applied along the nanotube axis [3], see Fig. 1(a). The phase gives rise to resistance oscillations in a varying magnetic flux [4]. Since it changes k ⊥ , it also changes the energy E(k) of an electronic state, through its dependence on the wave vector k = (k , k ⊥ (B )). Such a magnetic field dependence of the energies has been observed through beatings in Fabry-Perot patterns [5], or in the characteristic evolution of excitation spectra of CNT quantum dots in the sequential tunneling [6-9] and Kondo [10-15] regimes.In this Letter we show that the combination of the bipartite honeycomb lattice, the cylindrical topology of the nanotubes, and the confinement in the quantum dot intertwines the usually separable parallel and transverse components of the wave function. This leads to unusual tunability of the wave function in the direction parallel to the magnetic field. Experimentally, it manifests in a pronounced variation of the conductanc...

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“…Our raw data is available to the interested reader [ 17 ] (for the used open source measurement package, see ref. [33]); we hope to inspire corresponding work.…”

Section: Resultsmentioning

confidence: 94%

From Transparent Conduction to Coulomb Blockade at Fixed Hole Number

Schmid

Stiller

Dirnaichner

et al. 2020

Physica Status Solidi (b)

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A complex set of transport spectroscopy data on a clean single‐wall carbon nanotube device in high magnetic fields is presented. At zero axial field, the device displays in hole conduction with increasingly negative gate voltage a fast transition toward high contact transparency and eventually Fabry–Pérot interference of conductance. When increasing the axial field component up to Bfalse∥=17 T, the contact transparency and the overall conductance are reduced all the way to Coulomb blockade, clearly displaying the subsequent charging with the first ten holes. The continuous transition between the transport regimes is dominated by a rich spectrum of Kondo‐like resonances, with distinct features in the stability diagrams.

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Lab::Measurement—A portable and extensible framework for controlling lab equipment and conducting measurements

Cited by 17 publications

References 9 publications

Coulomb Blockade Spectroscopy of a MoS₂ Nanotube

Coulomb Blockade Spectroscopy of a MoS₂ Nanotube

Shaping Electron Wave Functions in a Carbon Nanotube with a Parallel Magnetic Field

From Transparent Conduction to Coulomb Blockade at Fixed Hole Number

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Lab::Measurement—A portable and extensible framework for controlling lab equipment and conducting measurements

Cited by 17 publications

References 9 publications

Coulomb Blockade Spectroscopy of a MoS2 Nanotube

Coulomb Blockade Spectroscopy of a MoS2 Nanotube

Shaping Electron Wave Functions in a Carbon Nanotube with a Parallel Magnetic Field

From Transparent Conduction to Coulomb Blockade at Fixed Hole Number

Contact Info

Product

Resources

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Coulomb Blockade Spectroscopy of a MoS₂ Nanotube

Coulomb Blockade Spectroscopy of a MoS₂ Nanotube