标题： 声子，自旋-声子耦合以及通过六方锗纳米线晶格重取向机制的自旋弛豫 显示英文标题

标题： Acoustic phonons, spin-phonon coupling and spin relaxation via the lattice reorientation mechanism in hexagonal germanium nanowires

摘要： 自旋弛豫通过电子-声子相互作用是自旋量子比特的一种重要退相干机制。在这项工作中，我们研究了六角形（2H）锗中的自旋弛豫，这是一种新型的直接带隙半导体，显示出将高相干自旋量子比特与光学功能相结合的巨大潜力。专注于六角形锗纳米线中静电定义的量子点，我们（i）识别出可行的自旋量子比特实验的几何结构，（ii）计算纳米线的声子模式，并（iii）描述由于声子引起的晶格重新取向导致的空穴自旋量子比特的自旋弛豫，这是一种直接的自旋-声子耦合机制，在通常用于自旋量子比特的立方半导体（GaAs、立方硅、立方锗）中不存在。 我们得到自旋弛豫时间作为纳米线横截面、量子点限制长度和磁场的函数。对于实际参数，我们发现弛豫时间超过10毫秒，并且揭示了最大化弛豫时间的磁场方向取决于量子比特的拉莫尔频率。我们的结果有助于设计具有长量子比特弛豫时间的纳米线量子点实验。 显示英文摘要

摘要： Spin relaxation via electron-phonon interaction is an important decoherence mechanism for spin qubits. In this work, we study spin relaxation in hexagonal (2H) germanium, a novel direct-gap semiconductor showing great potential to combine highly coherent spin qubits with optical functionality. Focusing on electrostatically defined quantum dots in hexagonal germanium nanowires, we (i) identify geometries where spin qubit experiments are feasible, (ii) compute the nanowire phonon modes, and (iii) describe spin relaxation of hole spin qubits due to phonon-induced lattice reorientation, a direct spin-phonon coupling mechanism that is absent in cubic semiconductors typically used for spin qubits (GaAs, cubic Si, cubic Ge). We obtain the spin relaxation time as a function of nanowire cross section, quantum dot confinement length, and magnetic field. For realistic parameters, we find relaxation times above 10 ms, and reveal that the magnetic field direction maximizing the relaxation time depends on the qubit Larmor frequency. Our results facilitate the design of nanowire quantum dot experiments with long qubit relaxation times.