Coulomb Oscillations in a Gate-Controlled Few-Layer Graphene Quantum Dot

Area of Science:

• Quantum physics
• Materials science
• Condensed matter physics

Background:

• Graphene quantum dots (GQDs) are promising for spin qubits.
• Existing GQD fabrication methods (nanoribbons, etched nanostructures) suffer from disorder.
• Disorders limit the functionality of graphene-based quantum devices.

Purpose of the Study:

• To engineer GQDs with tunable barriers in few-layer graphene.
• To overcome limitations posed by edge and substrate-induced disorders.
• To investigate the magnetic field dependence of GQD energy spectra.

Main Methods:

• Confinement of quantum dots using local strain and electrostatic gating.
• Transport measurements to confirm barrier formation and band gap opening.
• Numerical simulations to model electrostatic gating effects and energy spectra.

Main Results:

• Tunable confinement barriers were successfully created in few-layer graphene.
• Electrostatic gating and local strain induced a band gap, forming confinement barriers.
• Experimental and simulated energy spectra showed complex Coulomb oscillations and kinks, indicating hybridized states.

Conclusions:

• The developed method allows for controlled GQD fabrication, overcoming disorder limitations.
• The observed spectral features confirm the hybridized nature of the energy levels in these GQDs.
• This work paves the way for advanced graphene-based quantum information processing devices.