Spin-valley coupling in single-electron bilayer graphene quantum dots

Understanding how the electron spin is coupled to orbital degrees of freedom, such as a valley degree of freedom in solid-state systems, is central to applications in spin-based electronics and quantum computation. Recent developments in the preparation of electrostatically-confined quantum dots in gapped bilayer graphene (BLG) enable to study the low-energy single-electron spectra in BLG quantum dots, which is crucial for potential spin and spin-valley qubit operations. Here, we present the observation of the spin-valley coupling in bilayer graphene quantum dots in the single-electron regime. By making use of highly-tunable double quantum dot devices we achieve an energy resolution allowing us to resolve the lifting of the fourfold spin and valley degeneracy by a Kane-Mele type spin-orbit coupling of approximate to 60 mu eV. Furthermore, we find an upper limit of a potentially disorder-induced mixing of the K and K' states below 20 mu eV.

Automated summary

Understanding the coupling of electron spin with orbital degrees of freedom is crucial for applications in spin-based electronics and quantum computation. Recent experiments in bilayer graphene quantum dots have demonstrated the observation of spin-valley coupling and the effect of Kane-Mele type spin-orbit coupling in lifting the degeneracy of spin and valley states. These findings provide important insights for potential advancements in spin and spin-valley qubit operations.