Gate-defined wires in twisted bilayer graphene: from electrical detection of inter-valley coherence to internally engineered Majorana modes

Abstract

Twisted bilayer graphene (TBG) realizes a highly tunable, strongly interacting system featuring superconductivity and various correlated insulating states. We establish gate-defined wires in TBG with proximity-induced spin-orbit coupling as $(i)$ a tool for revealing the nature of correlated insulators and $(ii)$ a platform for Majorana-based topological qubits. In particular, we show that the band structure of a gate-defined wire immersed in an `inter-valley coherent' correlated insulator inherits electrically detectable fingerprints of symmetry breaking native to the latter. Surrounding the wire by a superconducting TBG region on one side and an inter-valley coherent correlated insulator on the other further enables the formation of Majorana zero modes--possibly even at zero magnetic field depending on the precise symmetry-breaking order present. Our proposal not only introduces a highly gate-tunable topological qubit medium relying on internally generated proximity effects, but can also shed light on the Cooper-pairing mechanism in TBG.

7 pages, 39 pages appendix (v2: new references and additional discussion in appendix)

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Cited by in corpus (11)

• Detecting symmetry breaking in magic angle graphene using scanning tunneling microscopy
• Gate-Defined Topological Josephson Junctions in Bernal Bilayer Graphene
• Trions in Twisted Bilayer Graphene
• Gate-defined electron interferometer in bilayer graphene
• Majorana bound states in encapsulated bilayer graphene
• Symmetry-broken metallic orders in spin-orbit-coupled Bernal bilayer graphene
• Majorana zero modes in twisted transition metal dichalcogenides homobilayers
• Interface engineering of van der Waals heterostructures towards energy-efficient quantum devices operating at high temperatures
• Gate-defined single-electron transistors in twisted bilayer graphene
• An effective curved space-time geometric theory of generic twist angle graphene with application to a rotating bilayer configuration
• Surface acoustic wave-driven valley current generation in intervalley coherent states