Quantum Coherence Lab

Zumbühl Group

 

News from our Group

Just accepted in Nano Letters: "Template-assisted scalable nanowire networks"

Topological qubits based on Majorana fermions have the potential to revolutionize the emerging field of quantum computing by making information processing significantly more robust to decoherence. In this Letter, we report gold-free templated growth of III-V NWs by molecular beam epitaxy using an approach that enables patternable and highly regular branched NW arrays on a far greater scale than what has been reported thus far. Our approach relies on the lattice-mismatched growth of InAs on top of defect-free GaAs nanomembranes (NMs) yielding laterally-oriented, low-defect InAs and InGaAs NWs.
Nano Letters DOI:
10.1021/acs.nanolett.8b00554

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Master/Project thesis position available! Hands on a Spin Qubit Device: g-factor anisotropy in GaAs

We are looking for a motivated, talented and technology-savvy physics or nanoscience student for research of the theoretically predicted g-factor anisotropy in a lateral Gallium Arsenide (GaAs) quantum dot spin qubit device measured at sub-Kelvin temperature.

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European Microkelvin Platform in Nature Materials Reviews

The growing demands of quantum materials, engineering and technology make access to microkelvin temperatures ever more essential. Experience in Europe suggests that new working methods, encouraged by an imaginative funding atmosphere, can accelerate progress in this frontier field. Review by George Pickett and Christian Enss in Nature Materials.

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Template-assisted nanowire networks on arXiv!

Topological qubits based on Majorana fermions have the potential to revolutionize the emerging field of quantum computing by making information processing significantly more robust to decoherence. Nanowires (NWs) are a promising medium for hosting these kinds of qubits, though branched NWs are needed to perform qubit manipulations. Here we report gold-free templated growth of III-V NWs by molecular beam epitaxy using an approach that enables patternable and highly regular branched NW arrays on a far greater scale than what has been reported thus far. Friedl et al. ArXiv:1803.00647

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Edge state tunneling spectroscopy paper on arXiv!

One of the most intriguing and fundamental properties of topological materials is the correspondence between the conducting edge states and the gapped bulk spectrum. So far, it has been impossible to access the full evolution of edge states in a magnetic field with critical system parameters due to poor resolution, remnant bulk conductivity, or disorder. Here, we present a novel type of tunneling spectroscopy which allows us to track the center of mass edge state positions with great precision and which can discriminate even spatially overlapping states due to their differing momenta based on tunneling along an extended GaAs quantum wire with translational symmetry. This results in unprecedented spatial resolution of about 1 nm at Tesla fields, while keeping the driving bias in the low microV regime in linear response. Patlatiuk et al. arXiv:1802.03847.

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