Coherent Imaging of Quantum Solids Using a Computer-Generated Hologram

强大的成像方法为微/纳米世界打开了新的窗口，伴随着我们技术的爆炸式发展，推动了小型化趋势。为了克服这种前所未有的增长对环境的影响，我们需要新的低功耗计算和高效的清洁能源技术，这取决于新材料的发展。最近，x射线显微镜成为一种理想的工具，可以拥抱这些材料的研究机会，以应对现代社会的挑战。本项目旨在开发一种新的x射线全息方法来研究纳米尺度的量子固体。我们的目标是可视化这些材料宏观量子行为背后的微观结构。这项技术依靠计算机生成的全息图将入射的x射线分成参考光束和样本光束。当样品束穿过样品时，参考束在真空中传播，并被印上编码样品内部电子和磁性结构的相位信息。然后，相机捕获干涉图案，从中恢复样品的复值图像，空间分辨率低至<30 nm。图像中包含了样品的成分、密度和磁化等属性信息。该方法具有以下几个主要优点：(1)样品和参考光束不受预图案结构的定义，避免了耗时的样品制备；视场没有在物理上固定在预先选定的区域，从而可以对扩大的样本进行调查；（iii）样品和照明的分离允许极大灵活的实验能力，例如具有新可能性的反射几何；（iv）该方法与单镜头、纳米级超快速成像兼容。模拟结果支持我们提出的称为结构照明x射线全息（SIXH）的方法的可行性。SIXH将为x射线显微镜提供新的见解，但更重要的是，它将充分利用当前和未来的高相干光源。因此，它将对我们对量子固体和x射线科学的理解产生广泛的影响，其深远的应用将超越硬凝聚态物理。

Powerful imaging methods open new windows to the micro/nano-world, fuelling the miniaturization trend accompanied by an explosion in our technology. To overcome environmental impacts of this unprecedented growth, we need new low-power computing and efficient clean energy technologies contingent upon development of novel materials. Recently, X-ray microscopy emerged as an ideal tool to embrace such materials research opportunities to address modern societal challenges. This project aims to develop a new X-ray holography method to investigate quantum solids at the nanoscale. Our goal is to visualize microscopic textures that underlie the macroscopic quantum behavior of such materials. The technique depends on computer-generated holograms to split the incident X-rays into a reference beam and a sample beam. The reference beam propagates in the vacuum while the sample beam traverses the sample and is imprinted with phase information that encodes the internal electronic and magnetic structure of the specimen. A camera then captures the interference pattern from which a complex-valued image of the sample is recovered with a spatial resolution down to <30 nm. The image carries information about the samples’ properties such as composition, density, and magnetization. The proposed method has several key advantages: (i) the sample and reference beams are not defined by pre-patterned structures, avoiding the time-consuming sample preparation; (ii) The field of view is not physically anchored to a pre-selected region, allowing investigation of extended samples; (iii) The separation of the sample and the illumination allows vastly flexible experimental capabilities such as reflection geometry with new possibilities; (iv) The approach is compatible with single-shot, ultra-fast imaging at the nanoscale. Simulations support the viability of the proposed method we call the Structured Illumination X-ray Holography (SIXH). SIXH will provide new insights in X-ray microscopy, but more importantly, it critically leverages current and future high-coherence sources. Therefore, it is poised to have a broad impact on our understanding of quantum solids and X-ray science in general, with far-reaching applications extending beyond hard condensed matter physics.