Sandia National Laboratories, Albuquerque, NM 87123, United States of America.
Nanotechnology. 2019 May 24;30(21):215202. doi: 10.1088/1361-6528/ab061e. Epub 2019 Mar 14.
Even as today's most prominent spin-based qubit technologies are maturing in terms of capability and sophistication, there is growing interest in exploring alternate material platforms that may provide advantages, such as enhanced qubit control, longer coherence times, and improved extensibility. Recent advances in heterostructure material growth have opened new possibilities for employing hole spins in semiconductors for qubit applications. Undoped, strained Ge/SiGe quantum wells are promising candidate hosts for hole spin-based qubits due to their low disorder, large intrinsic spin-orbit coupling strength, and absence of valley states. Here, we use a simple one-layer gated device structure to demonstrate both a single quantum dot as well as coupling between two adjacent quantum dots. The hole effective mass in these undoped structures, m* ∼ 0.08 m , is significantly lower than for electrons in Si/SiGe, pointing to the possibility of enhanced tunnel couplings in quantum dots and favorable qubit-qubit interactions in an industry-compatible semiconductor platform.
尽管当今最先进的基于自旋的量子比特技术在性能和复杂性方面日趋成熟，但人们越来越感兴趣地探索替代材料平台，这些平台可能具有优势，例如增强的量子比特控制、更长的相干时间和更好的可扩展性。异质结构材料生长的最新进展为在半导体中利用空穴自旋开辟了新的可能性，用于量子比特应用。由于无掺杂、应变 Ge/SiGe 量子阱的无序性低、固有自旋轨道耦合强度大且不存在谷态，因此它们是基于空穴自旋的量子比特的有前途的候选宿主。在这里，我们使用简单的单层门控器件结构来演示单个量子点以及两个相邻量子点之间的耦合。这些无掺杂结构中的空穴有效质量 m*∼0.08m，明显低于 Si/SiGe 中的电子，这表明量子点中的隧道耦合可能增强，并且在与行业兼容的半导体平台中，量子比特-量子比特相互作用有利。
