Counting statistics of single electron transport in bilayer graphene quantum dots

Garreis, Rebekka; Daniel, Gerber, Jonas; Stará, Veronika; Tong, Chuyao; Gold, Carolin; Röösli, Marc P.; Watanabe, Kenji; Taniguchi, Takashi; Ensslin, Klaus; Ihn, Thomas; Kurzmann, Annika

doi:10.1103/physrevresearch.5.013042

Cited by 10 publications

(3 citation statements)

References 41 publications

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“…The ability to detect single electrons in the solid state is useful for a variety of applications, including spin qubit readout [1][2][3][4], electrical current and capacitance standards [5,6], studying cooper pair breaking [7][8][9], single-shot photodetection [10][11][12][13], and nanothermodynamics and fluctuations [14][15][16][17][18][19]. While many methods exist to detect charge, one of the main ways are by utilizing quantum dots (QD).…”

Section: Introductionmentioning

confidence: 99%

Quantum Dot Source-Drain Transport Response at Microwave Frequencies

Havir¹,

Haldar²,

Khan³

et al. 2023

Preprint

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Quantum dots are frequently used as charge sensitive devices in low temperature experiments to probe electric charge in mesoscopic conductors where the current running through the quantum dot is modulated by the nearby charge environment. Recent experiments have been operating these detectors using reflectometry measurements up to GHz frequencies rather than probing the low frequency current through the dot. In this work, we use an on-chip coplanar waveguide resonator to measure the source-drain transport response of two quantum dots at a frequency of 6 GHz, further increasing the bandwidth limit for charge detection. Similar to the low frequency domain, the response is here predominantly dissipative. For large tunnel coupling, the response is still governed by the low frequency conductance, in line with Landauer-Büttiker theory. For smaller couplings, our devices showcase two regimes where the high frequency response deviates from the low frequency limit and Landauer-Büttiker theory: When the photon energy exceeds the quantum dot resonance linewidth, degeneracy dependent plateaus emerge. These are reproduced by sequential tunneling calculations. In the other case with large asymmetry in the tunnel couplings, the high frequency response is two orders of magnitude larger than the low frequency conductance G, favoring the high frequency readout.

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Section: Introductionmentioning

confidence: 99%

Quantum Dot Source-Drain Transport Response at Microwave Frequencies

Havir¹,

Haldar²,

Khan³

et al. 2023

Preprint

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“…There has been a long‐standing interest in graphene‐based nanostructures due to carbon's low spin‐orbit and hyperfine coupling promising long coherence times. [ 1–3 ] Recently, advanced fabrication and gating techniques have enabled the experimental realization of electrostatically confined nanostructures in bilayer graphene, i.e., quantum channels, [ 4–8 ] dots, [ 9–29 ] Josephson junctions, interferometers, and superconducting quantum interference devices (SQUIDs), [ 30–35 ] in an endeavor to design bilayer graphene‐based nanostructures for future quantum technology applications.…”

Section: Introductionmentioning

confidence: 99%

Tuning Confined States and Valley G‐Factors by Quantum Dot Design in Bilayer Graphene

Mayer,

Knothe

2023

Physica Status Solidi (b)

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Electrostatically confined quantum dots in bilayer graphene have shown potential as building blocks for quantum technologies. To operate the dots, e.g., as qubits, a precise understanding and control of the confined states and their properties is required. Here, we perform large‐scale numerical characterization of confined quantum states in bilayer graphene dots over an extensive range of gate‐tunable parameters such as the dot size, depth, shape, and the bilayer graphene gap. We establish the dot states’ orbital degeneracy, wave function distribution, and valley g‐factor and provide the parametric dependencies to achieve different regimes. We find that the dot states are highly susceptible to gate‐dependent confinement and material parameters, enabling efficient tuning of confined states and valley g‐factor modulation by quantum dot design.This article is protected by copyright. All rights reserved.

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“…Because of these properties, bilayer graphene has become a rapidly developing material platform for spin and valley qubits. Crucial ingredients for quantum computing applications, including time-resolved charge detection , and switchable Pauli spin and valley blockade, − have been demonstrated in electrostatically defined bilayer graphene QDs. Spin lifetimes of up to 400 ms in these systems , are comparable to those of other semiconductor QD systems like III–V, − silicon- − and germanium- based heterostructures.…”

mentioning

confidence: 99%

Electric Dipole Coupling of a Bilayer Graphene Quantum Dot to a High-Impedance Microwave Resonator

Ruckriegel,

Gächter,

Kealhofer

et al. 2024

Nano Lett.

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We implement circuit quantum electrodynamics (cQED) with quantum dots in bilayer graphene, a maturing material platform that can host longlived spin and valley states. Our device combines a high-impedance (Z r ≈ 1 kΩ) superconducting microwave resonator with a double quantum dot electrostatically defined in a graphene-based van der Waals heterostructure. Electric dipole coupling between the subsystems allows the resonator to sense the electric susceptibility of the double quantum dot from which we reconstruct its charge stability diagram. We achieve sensitive and fast detection of the interdot transition with a signal-to-noise ratio of 3.5 within 1 μs integration time. The charge−photon interaction is quantified in the dispersive and resonant regimes by comparing the resonator response to input−output theory, yielding a coupling strength of g/2π = 49.7 MHz. Our results introduce cQED as a probe for quantum dots in van der Waals materials and indicate a path toward coherent charge−photon coupling with bilayer graphene quantum dots.

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Counting statistics of single electron transport in bilayer graphene quantum dots

Cited by 10 publications

References 41 publications

Quantum Dot Source-Drain Transport Response at Microwave Frequencies

Quantum Dot Source-Drain Transport Response at Microwave Frequencies

Tuning Confined States and Valley G‐Factors by Quantum Dot Design in Bilayer Graphene

Electric Dipole Coupling of a Bilayer Graphene Quantum Dot to a High-Impedance Microwave Resonator

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