Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

HL: Fachverband Halbleiterphysik

HL 9: Focus Session: Graphene quantum dots (joint session HL/TT)

HL 9.5: Hauptvortrag

Montag, 27. März 2023, 17:15–17:45, POT 251

Particle-hole symmetry protects spin-valley blockade in graphene quantum dots — •Christian Volk^1,2, Luca Banszerus^1,2, Samuel Möller^1,2, Katrin Hecker^1,2, Eike Icking^1,2, Kenji Watanabe³, Takashi Taniguchi⁴, Fabian Hassler⁵, and Christoph Stampfer^1,2 — ¹JARA-FIT and 2nd Institute of Physics, RWTH Aachen University — ²Peter Grünberg Institute (PGI-9), Forschungszentrum Jülich — ³Research Center for Functional Materials, NIMS, Tsukuba, Japan — ⁴International Center for Materials Nanoarchitectonics, NIMS, Tsukuba, Japan — ⁵JARA-Institute for Quantum Information, RWTH Aachen University

Particle-hole symmetry plays an important role for the characterization of topological phases in solid-state systems. Graphene is a prime example of a gapless particle-hole symmetric system. The intrinsic Kane-Mele spin-orbit coupling in graphene leads to a lifting of the spin-valley degeneracy and renders graphene a topological insulator in a quantum spin-Hall phase while preserving particle-hole symmetry.

Here, we show that the Kane-Mele spin-orbit gap leads to a lifting of the spin-valley degeneracy in bilayer graphene quantum dots, resulting in Kramer's doublets with different ordering for electron and hole states preserving particle-hole symmetry. We observe the creation of single electron-hole pairs with opposite quantum numbers and use the electron-hole symmetry to achieve a protected spin-valley blockade in electron-hole double quantum dots. The latter will allow spin-to-charge and valley-to-charge conversion, which is essential for the operation of spin and valley qubits.