硅FinFET双量子点中各向异性磁响应的对称性选择性应变控制
Symmetry-Selective Strain Control of Anisotropic Magnetic Response in a Silicon FinFET Double Quantum Dot
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中文总结 AI 辅助
该研究结合理论计算，揭示了硅FinFET双量子点的应变张量分量与空间对称性对磁响应的调控机制，为耦合空穴自旋量子比特的磁响应控制提供了理论依据。
中文摘要 AI 辅助
在制造与冷却过程中，硅FinFET等三维量子点结构会自然产生应变，这种应变在双量子点中尤为重要，因为两个量子点可能承受不同的局域应变，进而产生不同的磁响应。为了探究这种量子点间应变差如何影响耦合空穴自旋，我们结合基于六带k·p模型的三维泊松-薛定谔计算与组态相互作用，从理论上研究了硅FinFET双量子点的局域g张量。我们发现，应变的影响取决于其张量分量与空间对称性：对于对角分量ε_yy和ε_zz，应变主要改变主g值，仅使最大响应轴产生微小开口；而剪切分量ε_yz还可改变局域磁响应的取向。当应变分布保持横向镜面对称时，剪切诱导的旋转会被强烈抑制，打破这一局域约束则会产生显著的非对角响应，并旋转主磁轴。仅塞曼项的计算也呈现出相同的分量与对称性选择趋势，表明价带塞曼耦合足以产生这些现象，而完整哈密顿量决定其定量表达。综上，这些结果表明，可利用应变的张量分量与空间对称性来控制耦合空穴自旋量子比特中磁响应的幅度与取向。
英文摘要
Strain naturally develops in three-dimensional quantum-dot structures such as silicon FinFETs during fabrication and cooling. Such strain becomes especially important in a double quantum dot, because the two dots can experience different local strain and therefore acquire different magnetic responses. To understand how this dot-to-dot strain difference affects coupled hole spins, we theoretically study the local \(g\) tensors of a silicon FinFET double quantum dot by combining a three-dimensional Poisson--Schrödinger calculation based on a six-band \(k\!\cdot\!p\) model with configuration interaction. We find that the effect of strain depends on both its tensor component and its spatial symmetry. For the diagonal components \(ε_{yy}\) and \(ε_{zz}\), strain mainly changes the principal \(g\) values, with only a small opening of the maximum-response axes. In contrast, the shear component \(ε_{yz}\) can also change the orientation of the local magnetic response. When the strain profile preserves the transverse mirror symmetry, the shear-induced rotation is strongly suppressed. Breaking this local constraint permits a pronounced off-diagonal response and rotates the principal magnetic axes. The same component- and symmetry-selected trends appear in a Zeeman-only calculation, showing that the valence-band Zeeman coupling is sufficient to generate them, while the full Hamiltonian determines their quantitative expression. Together, these results show how the tensor component and spatial symmetry of strain can be used to control both the magnitude and orientation of the magnetic response in coupled hole-spin qubits.
