Long-range spin-coherence in a strongly-coupled all electronic dot-cavity system

Abstract

We present a theoretical analysis of spin-coherent electronic transport across a mesoscopic dot-cavity system. Such spin-coherent transport has been recently demonstrated in an experiment with a dot-cavity hybrid implemented in a high-mobility two-dimensional electron gas [C. Rössler et al., Phys. Rev. Lett. 115, 166603 (2015)] and its spectroscopic signatures have been interpreted in terms of a competition between Kondo-type dot-lead and molecular-type dot-cavity singlet-formation. Our analysis brings forward all the transport features observed in the experiments and supports the claim that a spin-coherent molecular singlet forms across the full extent of the dot-cavity device. Our model analysis includes: (i) a single-particle numerical investigation of the two-dimensional geometry, its quantum-coral-type eigenstates and associated spectroscopic transport features, (ii) the derivation of an effective interacting model based on the observations of the numerical and experimental studies, and (iii) the prediction of transport characteristics through the device using a combination of a master-equation approach on top of exact eigenstates of the dot-cavity system, and an equation-of-motion analysis that includes Kondo physics. The latter provides additional temperature scaling predictions for the many-body phase transition between molecular- and Kondo-singlet formation and its associated transport signatures.

arXiv comment22 pages, 11 figures, published version

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• Open quantum systems beyond Fermi's golden rule: Diagrammatic expansion of the steady-state time-convolutionless master equation
• Entanglement based observables for quantum impurities
• Cavity-mediated coherent coupling between distant quantum dots
• Signatures of folded branches in the scanning gate microscopy of ballistic electronic cavities
• Coherent exchange-coupled nonlocal Kondo impurities
• Magnetoresistance in an electronic cavity coupled to one-dimensional systems
• Imaging signatures of the local density of states in an electronic cavity
• Transport spectroscopy of singlet-triplet quantum dot states coupled to electronic cavities
• Unraveling screening mechanisms in Kondo impurities using an NRG-MPS-based method