We report an experimental study of quantum point contacts defined in a high-quality strained germanium quantum well with layered electric gates. At a zero magnetic field, we observed quantized conductance plateaus in units of 2e²/h. Bias-spectroscopy measurements reveal that the energy spacing between successive one-dimensional subbands ranges from 1.5 to 5 meV as a consequence of the small effective mass of the holes and the narrow gate constrictions. At finite magnetic fields perpendicular to the device plane, the edges of the conductance plateaus get split due to the Zeeman effect and Landé g factors were estimated to be ∼6.6 for the holes in the germanium quantum well. We demonstrate that all quantum point contacts in the same device have comparable performances, indicating a reliable and reproducible device fabrication process. Thus, our work lays a foundation for investigating multiple forefronts of physics in germanium-based quantum devices that require quantum point contacts as building blocks.

中文翻译：

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锗量子阱中栅极定义的量子点接触

我们报告了在具有分层电门的高质量应变锗量子阱中定义的量子点接触的实验研究。在零磁场下，我们观察到以 2 e ² / h为单位的量子化电导平台。偏置光谱测量表明，由于空穴有效质量小和栅极狭窄，连续一维子带之间的能量间距范围为 1.5 至 5 meV。在垂直于器件平面的有限磁场下，电导平台的边缘由于塞曼效应而分裂，并且对于锗量子阱中的孔，朗德g因子估计为 ∼6.6。我们证明同一器件中的所有量子点接触都具有可比的性能，这表明器件制造工艺可靠且可重复。因此，我们的工作为研究需要量子点接触作为构建块的基于锗的量子器件的多个物理学前沿奠定了基础。