发表机构
University of Science and Technology of China（中国科学技术大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究基于自旋-轨道-角动量耦合玻色-爱因斯坦凝聚体的非厄米动力学构建可调例外点传感平台，实现量子费舍尔信息增强，为量子传感提供实验可行途径。
AI 中文摘要
例外点（EPs）可诱导对微弱扰动的大幅放大响应，但传统非厄米系统中增强的光谱灵敏度未必能转化为量子极限传感性能的提升，因为伴随存在增益与损耗噪声。本研究基于自旋-轨道-角动量耦合玻色-爱因斯坦凝聚体（BEC）的本征非厄米玻戈留波夫动力学，构建了可调EP传感平台。从完全厄米的微观哈密顿量出发，推导得到具有宇称-时间（PT）对称性的玻戈留波夫动力学矩阵，其EP可通过拉曼耦合与相互作用参数进行调控。研究识别了多个EP并绘制了它们的轨迹及相关稳定性景观，揭示了当从PT对称稳定区域趋近EP时，量子费舍尔信息会显著增强。进一步发现，二阶EP附近的能隙打开速率是比较EP传感性能的有效相对指标，而高阶EP未必能从稳定区域实现；此外，两个二阶EP可被调谐至重叠，使其传感贡献叠加，实现总量子费舍尔信息的线性增强。最终表明，自旋密度测量可接近量子费舍尔信息极限，为BEC中可调EP增强量子传感提供了实验可行的途径。
英文摘要
Exceptional points (EPs) can induce strongly amplified responses to weak perturbations, but enhanced spectral sensitivity in conventional non-Hermitian systems does not necessarily translate into improved quantum-limited sensing because of the associated gain and loss noise. Here, we investigate a tunable EP sensing platform based on the intrinsic non-Hermitian Bogoliubov dynamics of a spin-orbit-angular-momentum-coupled Bose-Einstein condensate. Starting from a fully Hermitian microscopic Hamiltonian, we derive a Bogoliubov dynamical matrix that exhibits parity-time (PT) symmetry, with EPs tunable through the Raman coupling and interaction parameters. We identify multiple EPs and map their trajectories and associated stability landscapes, revealing strong quantum Fisher information enhancement when the EPs are approached from the PT-symmetric stable regime. We further find that the gap-opening rate around a second-order EP provides a useful relative indicator for comparing the sensing performance of EPs, while higher-order EPs are not necessarily accessible from the stable regime. Moreover, two second-order EPs can be tuned to overlap, allowing their sensing contributions to add and yielding a linear enhancement of the total quantum Fisher information. Finally, we show that a spin-density measurement can approach the quantum Fisher information limit, providing an experimentally accessible route to tunable EP-enhanced quantum sensing in Bose-Einstein condensates.
Comments12 pages, 8 figures
