Particle-hole symmetry protects spin-valley blockade in graphene quantum dots

• URL: http://arxiv.org/abs/2303.10201v1
• Date: Fri, 17 Mar 2023 18:29:29 GMT
• Title: Particle-hole symmetry protects spin-valley blockade in graphene quantum dots
• Authors: Luca Banszerus, Samuel M\"oller, Katrin Hecker, Eike Icking, Kenji Watanabe, Takashi Taniguchi, Fabian Hassler, Christian Volk, Christoph Stampfer
• Abstract summary: Bilayer graphene allows realizing electron-hole double quantum-dots that exhibit nearly perfect particle-hole symmetry. This symmetry results in a protected single-particle spin-valley blockade. The latter will allow robust spin-to-charge conversion and valley-to-charge conversion.
• Score: 0.33727511459109777
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Particle-hole symmetry plays an important role for the characterization of topological phases in solid-state systems. It is found, for example, in free-fermion systems at half filling, and it is closely related to the notion of antiparticles in relativistic field theories. In the low energy limit, graphene is a prime example of a gapless particle-hole symmetric system described by an effective Dirac equation, where topological phases can be understood by studying ways to open a gap by preserving (or breaking) symmetries. An important example is the intrinsic Kane-Mele spin-orbit gap of graphene, which 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 bilayer graphene allows realizing electron-hole double quantum-dots that exhibit nearly perfect particle-hole symmetry, where transport occurs via the creation and annihilation of single electron-hole pairs with opposite quantum numbers. Moreover, we show that this particle-hole symmetry results in a protected single-particle spin-valley blockade. The latter will allow robust spin-to-charge conversion and valley-to-charge conversion, which is essential for the operation of spin and valley qubits.

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