Tunable few-electron double quantum dots and Klein tunnelling in ultra-clean carbon nanotubes

Abstract

Quantum dots defined in carbon nanotubes are a platform for both basic scientific studies and research into new device applications. In particular, they have unique properties that make them attractive for studying the coherent properties of single electron spins. To perform such experiments it is necessary to confine a single electron in a quantum dot with highly tunable barriers, but disorder has until now prevented tunable nanotube-based quantum-dot devices from reaching the single-electron regime. Here, we use local gate voltages applied to an ultra-clean suspended nanotube to confine a single electron in both a single quantum dot and, for the first time, in a tunable double quantum dot. This tunability is limited by a novel type of tunnelling that is analogous to that in the Klein paradox of relativistic quantum mechanics.

21 pages including supplementary information

References in corpus (6)

• Single-shot read-out of an individual electron spin in a quantum dot
• Spin qubits in graphene quantum dots
• Coherent control of a single electron spin with electric fields
• Coupling of Spin and Orbital Motion of Electrons in Carbon Nanotubes
• Spin-orbit interaction and anomalous spin relaxation in carbon nanotube quantum dots
• Universal phase shift and non-exponential decay of driven single-spin oscillations

Cited by in corpus (2)

• Carbon nanotubes as ultra-high quality factor mechanical resonators
• Hyperfine interaction and electron-spin decoherence in graphene and carbon nanotube quantum dots