近日，德国雷根斯堡大学的Y. A. Gerasimenko&M.A.Huber&J.Wilhelm及其研究团队取得一项新进展。经过不懈努力，他们研制出原子长度尺度上的全光学亚周期显微镜。相关研究成果已于2024年5月8日在国际权威学术期刊《自然》上发表。

该研究团队在尖端受限的倏逝场内利用极端的原子非线性，推动全光学显微镜到皮米空间和飞秒时间分辨率。在这些尺度上，研究人员发现了一种前所未有的、高效的非经典近场响应，与光的矢量势相一致，并且严格限于原子尺度。这种超快信号的特征是光学相位延迟约为π/2，便于直接监测隧道动力学。研究人员通过对隐藏在原子力显微镜下的纳米级缺陷进行成像，以及对半导体范德华材料上的电流瞬态进行亚周期采样，展示了该光学概念的能力。这项研究结果有助于在导电和绝缘量子材料的最终短时空尺度上，获得量子光物质相互作用和电子动力学。

据悉，将光学显微镜带到尽可能短的长度和时间尺度一直是一个长期追求的目标，将纳米级的基本动力学与凝聚态物质的宏观功能联系起来。超分辨率显微镜利用光学非线性绕过了远场衍射极限。通过利用与尖端受限的倏逝光场的线性相互作用，近场显微镜达到了更高的分辨率，通过探索运动中的纳米世界促进了一个充满活力的研究领域。然而，纳米大小的尖端的有限半径阻碍了原子分辨率的实现。

附：英文原文

Title: All-optical subcycle microscopy on atomic length scales

Author: Siday, T., Hayes, J., Schiegl, F., Sandner, F., Menden, P., Bergbauer, V., Zizlsperger, M., Nerreter, S., Lingl, S., Repp, J., Wilhelm, J., Huber, M. A., Gerasimenko, Y. A., Huber, R.

Issue&Volume: 2024-05-08

Abstract: Bringing optical microscopy to the shortest possible length and time scales has been a long-sought goal, connecting nanoscopic elementary dynamics with the macroscopic functionalities of condensed matter. Super-resolution microscopy has circumvented the far-field diffraction limit by harnessing optical nonlinearities. By exploiting linear interaction with tip-confined evanescent light fields, near-field microscopy has reached even higher resolution, prompting a vibrant research field by exploring the nanocosm in motion. Yet the finite radius of the nanometre-sized tip apex has prevented access to atomic resolution. Here we leverage extreme atomic nonlinearities within tip-confined evanescent fields to push all-optical microscopy to picometric spatial and femtosecond temporal resolution. On these scales, we discover an unprecedented and efficient non-classical near-field response, in phase with the vector potential of light and strictly confined to atomic dimensions. This ultrafast signal is characterized by an optical phase delay of approximately π/2 and facilitates direct monitoring of tunnelling dynamics. We showcase the power of our optical concept by imaging nanometre-sized defects hidden to atomic force microscopy and by subcycle sampling of current transients on a semiconducting van der Waals material. Our results facilitate access to quantum light–matter interaction and electronic dynamics at ultimately short spatio-temporal scales in both conductive and insulating quantum materials.

DOI: 10.1038/s41586-024-07355-7

Source: https://www.nature.com/articles/s41586-024-07355-7