University of Basel

Department
of Physics

Quantum Coherence Lab - Zumbühl Group

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New on arXiv: Closed-form weak localization with arbitrary Rashba and Dresselhaus interactions

We derive a closed-form expression for the weak localization corrections to the magnetoconductivity of a 2D electron system with arbitrary Rashba and both linear and cubic Dresselhaus spin-orbit interactions in a perpendicular magnetic…
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New ArXiv submission: Effciently measuring a quantum device using machine learning

Tuning quantum devices is becoming time-consuming as systems are scaled up, e.g. to numerous gates or contacts, and will soon become intractable without automation. Here, we present measurements on a quantum dot done by a machine learning…
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"Ambipolar dots in Si finFETs..." published in Appl. Phys. Letters

Ambipolar quantum dots in silicon fin fi eld-eff ect transistors are defined using exclusively standard complementary metal-oxide-semiconductor fabrication techniques. We demonstrate stable quantum dot operation in the few charge carrier…
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"Evolution of the Quantum Hall bulk spectrum" published in Nature Communications!

Using a GaAs cleaved-edge quantum wire, we perform spectroscopy revealing the momentum and position of the quantum Hall edge states with unprecedented precision. We present models in excellent agreement with the experiment—thus providing…
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"Hyperfine-phonon spin relaxation" published in Nature Communications!

Understanding and control of the spin relaxation time T1 is a key challenge for spin qubits, setting the fundamental upper limit to the qubit coherence and readout fidelity. We establish the prediction of hyperfine-phonon spin relaxation…
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Pulished in Appl. Phys. Letters: Ge/Si quantum dots

Published online on Aug 15 in Applied Physics Letters, our paper on gate defined quantum dots in Ge/Si nanowires, with single, double and triple dots, Pauli spin blockade, and signatures of a single hole quantum dot. Appl. Phys. Lett. 113,…
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Spin-orbit and g-factor effects in gate define quantum dots

We analyze orbital effects of an in-plane magnetic field on the spin structure of states of a gated quantum dot. Starting with a k.p Hamiltonian, we perturbatively calculate these effects for the conduction band of GaAs. We quantify…
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Ambipolar quantum dots in undoped silicon fin field-effect transistors: new arXiv submission

We integrate ambipolar quantum dots in silicon fin fi eld-eff ect transistors using exclusively standard complementary metal-oxide-semiconductor fabrication techniques. We realize ambipolarity by using a metallic nickel silicide with Fermi…
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Open Positions

We are looking for motivated and talented physicists for diverse projects. Please head over to the positions page for further information on the various projects.
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Single, double, and triple quantum dots in Ge/Si nanowires: new arXiv submission

We report highly tunable control of holes in Ge/Si core/shell nanowires (NWs). We demonstratethe a bility to create single quantum dots (QDs) of various sizes, with low hole occupation numbers and clearly observable excited states. For the…
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Two new manuscripts on arXiv, on Quantum-Dot Orbital-Spectroscopy with In-Plane Magnetic Fields!

Semiconductor spin qubits are leading candidates for quantum computation. Despite impressive progress over two decades, a tool to characterize the orbitals hosting the spin is lacking. Here, we demonstrate a spectroscopy method for quasi-2D…
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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…
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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…
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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…
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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…
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