自组装量子点中空穴自旋量子比特的光学退相干的量子器件模拟
Quantum-Device Simulation of Optical Decoherence of Hole-Spin Qubits in Self-Assembled Quantum Dots
AI总结：
本文开发器件级建模工作流，模拟自组装量子点中空穴自旋量子比特的光学退相干，揭示磁场、光功率、量子点高度对拉比振荡的影响，提出需协同优化器件相关参数以抑制退相干。
AI中文摘要：
自旋-光子界面是量子技术中远距离自旋量子比特间通信的关键，但带间光激发也会阻尼半导体自组装量子点（SAQD）中电驱动的空穴自旋拉比振荡。本文报道一种器件级建模工作流，该工作流将真实SAQD几何结构、多带电子结构分析与电驱动自旋控制、带间光跃迁及开放系统动力学模型相集成，可实现对重复带间吸收-发射循环产生的拉比振荡阻尼的器件级估算。以受沿SAQD生长方向的均匀磁场$B_0$作用的门控GaAs SAQD为例，本文预测了空穴自旋量子比特的拉比频率及其在外加光照下的阻尼：在$B_0=2$ T时，计算得到空穴自旋拉比频率为37.3 MHz；当电驱动SAQD被中心波长790 nm的宽带发光二极管（LED）照射时，将光功率从0.3 mW提升至1.5 mW，会使拉比振荡衰减时间从90.3 ns缩短至17.5 ns。增大SAQD高度会减小电子-空穴重叠度，从而降低发射率，但产生的红移会使带间跃迁与LED光谱的光谱重叠度增强，进而提高重复吸收-发射循环的速率，加剧光子诱导的拉比振荡阻尼。研究结果表明，半导体自旋-光子器件中需对几何结构、自旋控制条件及照射光谱进行协同优化。
英文摘要：
Spin-photon interfaces are essential for communications between distant spin qubits in quantum technologies, but the interband optical excitation can also damp electrically driven hole-spin Rabi oscillations in semiconductor self-assembled quantum dots (SAQDs). We report a device-level modeling workflow that integrates realistic SAQD geometry and multiband electronic-structure analysis with models of electrically driven spin control, interband optical transitions, and open-system dynamics. This workflow enables device-level estimation of Rabi-oscillation damping arising from repeated interband absorption-emission cycles. As an example, for a gated GaAs SAQD subjected to a uniform magnetic field $B_0$ along the growth direction of the SAQD, we predict the Rabi frequency of the hole spin qubit and its damping under external illumination. At $B_0=2$ T, the calculations yield a hole-spin Rabi frequency of 37.3 MHz. When the electrically driven SAQD is illuminated by a broadband LED centered at a wavelength of 790 nm, increasing the optical power from 0.3 to 1.5 mW shortens the Rabi-oscillation decay time from 90.3 to 17.5 ns. Increasing the SAQD height reduces the electron-hole overlap and thus the emission rate, but the resulting redshift moves the interband transitions into stronger spectral overlap with the LED spectrum, thereby increasing the rate of repeated absorption-emission cycles and enhancing photon-induced Rabi-oscillation damping. The results show that geometry, spin-control conditions, and illumination spectrum should be co-optimized in semiconductor spin-photon devices.
