Elektrische Dipol-Spin-Resonanz in Graphen-Quantenpunkten

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The main goal of this project is to explore spin states and spin decoherence times in graphene quantum dots. In particular, we will focus on testing electric dipole spin resonance (EDSR) in state-of-the-art graphene quantum dots for investigating the limitations of spin lifetimes in these carbon-based quantum devices. Graphene quantum dots have been identified as attractive candidates for hosting solid-state quantum bits because, thanks to the predicted weak spin-orbit and hyperfine interaction, they might allow spin qubits with long coherence times. Etched graphene quantum dots have been extensively investigated with respect to their excitation spectrum, spin-filling sequence and electron-hole crossover. However, their spin relaxation dynamics remain largely unexplored. This is mainly due to challenges in device fabrication, in particular concerning the control of carrier confinement and the tunability of the tunnelling barriers, both crucial to experimentally investigate decoherence times. Recently, we demonstrated pulse-gate experiments on advanced graphene quantum dot devices, where transient current measurements allowed estimating a lower bound for the charge relaxation time. For moving towards spin relaxation experiments we propose to investigate EDSR on our most advanced graphene quantum dots, with the ultimate goal of controlling individual spin states. This technique has been shown to work also without Pauli-spin-blockade, which so far has not been observed in graphene quantum dots.