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 experimentally, by measuring T1 over an unprecedented range of magnetic fields and report a maximum T1=57±15 s at the lowest fields, setting a new record for the spin lifetime in a nanostructure. Published on Aug 27 in Nature Communiations, with UniNews media release.
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).
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
We integrate ambipolar quantum dots in silicon fin field-effect 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