Quantum Coherence Lab

Zumbühl Group

 

News from our Group

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, 073102 (2018).

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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 several corrections to the g-tensor and reveal their relative importance and find numerous terms. The Rashba, Dresselhaus and isotropic terms give the largest contributions in magnitude, up to 5% or 10% of the bulk value at zero field. Stano et al., arXiv:1808.03963

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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 level close to the silicon mid-gap position. We demonstrate stable quantum dot operation in the few charge carrier Coulomb blockade regime for both electrons and holes, opening the way for spin qubits hosted in such fin transistors. arXiv:1807.04121

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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 smallest dot size we observe indications of single-hole occupation. In the double quantum dot con guration we observe Pauli spin blockade (PSB). These results open the way towards hole spin qubits. arXiv:1805.02532

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