Tunable g factor and phonon-mediated hole spin relaxation in Ge/Si nanowire quantum dots

Abstract

We theoretically consider g factor and spin lifetimes of holes in a longitudinal Ge/Si core/shell nanowire quantum dot that is exposed to external magnetic and electric fields. For the ground states, we find a large anisotropy of the g factor which is highly tunable by applying electric fields. This tunability depends strongly on the direction of the electric field with respect to the magnetic field. We calculate the single-phonon hole spin relaxation times T1 for zero and small electric fields and propose an optimal setup in which very large T1 of the order of tens of milliseconds can be reached. Increasing the relative shell thickness or the longitudinal confinement length further prolongs T1. In the absence of electric fields, the dephasing vanishes and the decoherence time T2 is determined by T2 = 2 T1.

7 pages, 4 figures

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• Majorana Fermions in Ge/Si Hole Nanowires
• Recent advances in hole-spin qubits
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• Anisotropic Pauli spin blockade in hole quantum dots
• Gate-Tunable Spin-Orbit Coupling in a Germanium Hole Double Quantum Dot
• Hole spin qubits in thin curved quantum wells
• Acoustic phonons and strain in core/shell nanowires
• Exchange interaction of hole-spin qubits in double quantum dots in highly anisotropic semiconductors
• Electrical operation of hole spin qubits in planar MOS silicon quantum dots
• Modelling of spin decoherence in a Si hole qubit perturbed by a single charge fluctuator
• Microscopic analysis of proximity-induced superconductivity and metallization effects in superconductor-germanium hole nanowires
• A Multiscale Simulation Approach for Germanium-Hole-Based Quantum Processor
• Strongly Interacting Holes in Ge/Si Nanowires
• Charge-sensing of a Ge/Si core/shell nanowire double quantum dot using a high-impedance superconducting resonator
• Low-energy hole subband dispersions in a cylindrical Ge nanowire: the effects of the nanowire growth direction
• Electrical manipulation of a hole `spin'-orbit qubit in nanowire quantum dot: the nontrivial magnetic field effects
• Hidden anisotropy controls spin-photon entanglement in a charged quantum dot
• Magnetic-field dependence of spin-phonon relaxation and dephasing due to g-factor fluctuations from first principles
• Hole subband dispersions and strong `spin'-orbit coupling in a cylindrical Ge nanowire
• Acoustic phonons, spin-phonon coupling and spin relaxation via the lattice reorientation mechanism in hexagonal germanium nanowires
• Anomalous zero-field splitting for hole spin qubits in Si and Ge quantum dots
• Spin qubit shuttling between coupled quantum dots with inhomogeneous Landé g-tensors
• Disentangling orbital and confinement contributions to $g$-factor in Ge/SiGe hole quantum dots