量子点分子中杂化轨道的可调g因子
Tunable g-Factors of Hybridized Orbitals in a Quantum Dot Molecule
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中文总结 AI 辅助
本研究利用偏振分辨磁光致发光光谱测量InGaAs量子点分子中负电荷三激子的g因子随栅极电压的变化，结合八带k·p模型实现对g因子的电场调控，为生成二维光子簇态提供了新方法。
中文摘要 AI 辅助
控制光学活性量子点分子（QDM）中轨道自旋态g因子的能力，是生成具有高维纠缠结构的高保真多光子簇态的前提。依赖两个耦合自旋的协议需要了解g因子及其对外部控制参数的依赖性。隧穿耦合量子点之间的g因子不匹配会导致耦合自旋态发生不必要的退相位，因此精确表征和电压控制至关重要。在此，我们利用偏振分辨磁光致发光光谱，测量了单个InGaAs量子点分子中负电荷三激子X⁻的电子和空穴g因子随栅极电压的变化。电子g因子在隧穿共振处表现出明显的阶跃式变化，从gₑ = -0.336±0.008转变为gₑ = -0.389±0.003，为分子轨道形成以及波函数定位从下量子点向上量子点的转移提供了直接的光谱指纹。相比之下，空穴g因子几乎保持恒定，约为gₕ ≈ 0.094±0.007，在反交叉电压附近表现出微弱调制，这归因于隧穿电子通过库仑作用对波函数的形变。我们的结果可由八带k·p模型定量复现，确立了三激子g因子的电场控制作为一种实用工具，可独立调控单个量子点的塞曼分裂，并为确定性生成二维光子簇态开辟了新途径。
英文摘要
The ability to control the $g$-factors of orbital spin states in optically active quantum dot molecules (QDMs) is a prerequisite for the high-fidelity generation of multi-photonic cluster states with higher-dimensional entanglement structure. Protocols that rely on two coupled spins require knowledge of the $g$-factor and its dependence on external control parameters. Mismatches in the $g$-factor between tunnel-coupled dots introduce unwanted dephasing of coupled spin-states, making precise characterization and voltage control essential. Here, we measure the gate voltage dependence of the electron and hole $g$-factors of negatively charged trions $X^{-}$ in a single InGaAs QDM using polarization-resolved magneto-photoluminescence spectroscopy. The electron $g$-factor exhibits a pronounced step-like change at the tunneling resonance, shifting from $g_\mathrm{e} = -0.336\pm 0.008$ to $g_\mathrm{e} = -0.389\pm 0.003$, providing a direct spectroscopic fingerprint of molecular orbital formation and a shift of the wavefunction localization from the lower to the upper dot. In contrast, the hole $g$-factor remains nearly constant at $g_\mathrm{h} \approx 0.094 \pm 0.007$, exhibiting a weak modulation near the anticrossing voltages attributed to Coulomb-mediated deformation of the wavefunction by the tunneling electron. Our results are quantitatively reproduced by an eight-band $\mathbf{k}{\cdot}\mathbf{p}$ model, establishing electric-field control of the trion $g$-factors as a practical tool for independently tuning the Zeeman splitting of individual dots and opening new pathways towards the deterministic generation of two-dimensional photonic cluster states.
