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arXiv · 2311.10188

Gate modulation of the hole singlet-triplet qubit frequency in germanium

John Rooney·Zhentao Luo·Lucas E. A. Stehouwer·Giordano Scappucci·Menno Veldhorst·Hong-Wen Jiang
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Abstract

Spin qubits in germanium gate-defined quantum dots have made considerable progress within the last few years, partially due to their strong spin-orbit coupling and site-dependent $g$-tensors. While this characteristic of the $g$-factors removes the need for micromagnets and allows for the possibility of all-electric qubit control, relying on these $g$-tensors necessitates the need to understand their sensitivity to the confinement potential that defines the quantum dots. Here, we demonstrate a $S-T\_$ qubit whose frequency is a strong function of the voltage applied to the barrier gate shared by the quantum dots. We find a $g$-factor that can be approximately increased by an order of magnitude adjusting the barrier gate voltage only by 12 mV. We attribute the strong dependence to a variable strain profile in our device. This work not only reinforces previous findings that site-dependent $g$-tensors in germanium can be utilized for qubit manipulation, but reveals the sensitivity and tunability these $g$-tensors have to the electrostatic confinement of the quantum dot.

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John Rooney, Zhentao Luo, Lucas E. A. Stehouwer, Giordano Scappucci, Menno Veldhorst, Hong-Wen Jiang. 2023-11-16. Gate modulation of the hole singlet-triplet qubit frequency in germanium. https://arxiv.org/abs/2311.10188

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