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FRI: Friday Contributed Sessions

FRI 11: Quantum 2D-Moiré and Rhombohedral van-der-Waals Systems: Contributed Session to Symposium

FRI 11.4: Talk

Friday, September 12, 2025, 11:30–11:45, ZHG104

Two-particle spin and valley blockade in graphene double quantum dots — •Christian Volk^1,2, Samuel Möller^1,2, Luca Banszerus^1,2, Katrin Hecker^1,2, Hubert Dulisch^1,2, Kenji Watanabe³, Takashi Taniguchi⁴, 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

Double quantum dots (DQDs) are promising building blocks for spin or valley qubits. The weak hyperfine interaction and the weak spin-orbit interaction in bilayer graphene (BLG) promise long spin coherence times. Additionally, the well tunable valley degree of freedom offers the possibility to create valley-based qubits in BLG DQDs. Efficient readout requires a spin- or valley-to-charge conversion, often provided by Pauli blockade. Thus, a comprehensive understanding of the limits and the tunablility of spin and valley blockade in BLG DQDs is necessary for evaluating their potential for hosting qubits.

Here, we show spin and valley blockade in two-electron BLG DQDs. Magnetotransport measurements reveal a rich level spectrum and we observe a magnetic field tunable spin and valley blockade, which is limited by the orbital splitting, the strength of the electron-electron interaction and the difference in the valley g-factors between the symmetric and antisymmetric two-particle orbital states. Our findings are supported by transport simulations following a rate equation approach.

Keywords: bilayer graphene; electron-electron interaction; spin-valley blockade; quantum dot