量子综合调控增强微纳自旋体系的量子相干性

在微纳尺寸自旋体系中，由于电子密度的局域效应，电子自旋同周围原子核自旋的耦合强度随原子核位置剧烈改变。当多次注入电子自旋时，原子核自旋的极化率呈现局域饱和现象；当多次注入电子自旋对时，原子核自旋间的关联被选择性加强。我们将结合解析简单模型和数值模拟物理体系的方法，以半导体量子点体系为对象，全面考虑原子核自旋间的偶极相互作用，细致系统地研究微纳尺寸自旋体系的长时间退相干过程以及原子核自旋动态极化和关联增强的物理过程，尤其关注原子核自旋的状态变化及长时间的稳态性质。利用高度极化的局域原子核自旋和加强的原子核自旋全局关联，结合动态退耦合的相干调控方法，设计综合的量子调控方案，增强电子（中心）自旋的相干性。本项目的研究成果将加深人们对实验现象和结果的理解，为进一步深入的实验提供物理支撑和理论指导，促进基于微纳尺寸自旋体系的量子存储器的应用研究。

Due to the localization of electron density in micro- and nano-size many-spin systems, the coupling strength between the central electron spin and surrounding nuclear spins changes drastically with the position of nuclei. The nuclear spin exhibits local polarization saturation with the increasing of the number of injected polarized electron spins; The correlation between nuclear spins is selectively enhanced by injecting electron spin pairs. By employing both analytical and numerical methods and including the nuclear dipolar interaction, we will investigate in detail and systematically the long time electron spin decoherence as well as the local saturation and the enhanced global correlation of nuclear spins in quantum dots, particularly focusing on the long time evolution and the stationary states of the nuclear spins. We will develop hybrid quantum control methods, which harness both the locally polarized nuclear spins or the global correlation and the dynamical decoupling protocols, to enhance the quantum coherence of the many spin systems. Our results will explain the observed phenomena and results in experiments, provide theoretical support and guidance for further experiments, and expedite the development of quantum memory based on micro- and nano-size many-spin systems.