AI 中文总结
本文提出将量子层析限制在电子轨道角动量子空间的简化方法，利用OAM分选器降低实验计算负担，通过结构化电子探针研究碳膜非弹性散射，揭示对称破缺效应等，为电子散射量子层析提供有效手段。
AI 中文摘要
量子系统的物理性质，无论是纯态还是混合态，都完全由其密度矩阵描述。通过投影测量恢复密度矩阵的过程称为量子态层析，它是量子光学和计量学的基石。该方法在透射电子显微镜中的应用，特别是对非弹性散射后电子束的表征，长期以来一直是一个挑战，原因在于扫描高维相空间的复杂性，所需测量次数随空间维度呈二次增长。本文提出一种简化方法，将层析限制在电子轨道角动量（OAM）子空间内。利用一种名为OAM分选器的电子光学器件，我们将相空间离散为一组可测量的有限态，从而显著降低了实验和计算负担。所得测量足以探测非弹性散射的基本特征。我们通过研究结构化电子探针激发碳膜中体等离激元的非弹性散射来演示该技术。结构化光束与OAM分辨量子层析的结合使用，揭示了对称破缺效应，并为散射量子态的相干性和演化提供了深入见解。对对角化密度矩阵的分析进一步揭示了诱导态跃迁的本质，证明了该方法在电子散射量子层析中的有效性。
英文摘要
The physical properties of a quantum system, whether pure or mixed, are described fully by its density matrix. Recovery of the density matrix through projective measurements -- referred to as quantum state tomography -- is a cornerstone of quantum optics and metrology. The implementation of this approach in transmission electron microscopy, in particular for the characterisation of an electron beam after inelastic scattering, has remained a longstanding challenge as a result of the complexity of scanning high-dimensional phase spaces, with the number of required measurements growing quadratically with space dimensionality. Here, we introduce a simplified approach by restricting tomography to the electron orbital angular momentum (OAM) subspace. By using an electron optical device known as an OAM sorter, we discretise the phase space into a finite set of measurable states, thus significantly reducing the experimental and computational burden. The resulting measurements suffice to probe essential features of inelastic scattering. We demonstrate the technique by studying the inelastic scattering of a structured electron probe exciting volume plasmons in a carbon film. The combined use of a structured beams and OAM-resolved quantum tomography reveals symmetry-breaking effects and offers insight into the coherence and evolution of the scattered quantum states. Analysis of the diagonalised density matrices further reveals the nature of the induced state transitions, demonstrating the power of the approach for quantum tomography of electron scattering.
Comments9 pages, 3 figure and is accompanied by Supplementary Information
