Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA.
Department of Chemistry, University of California, Irvine, CA 92697, USA.
Science. 2022 Apr 22;376(6591):401-405. doi: 10.1126/science.abn9220. Epub 2022 Apr 21.
A scanning tunneling microscope (STM) combined with a pump-probe femtosecond terahertz (THz) laser can enable coherence measurements of single molecules. We report THz pump-probe measurements that demonstrate quantum sensing based on a hydrogen (H) molecule in the cavity created with an STM tip near a surface. Atomic-scale spatial and femtosecond temporal resolutions were obtained from this quantum coherence. The H acts as a two-level system, with its coherent superposition exhibiting extreme sensitivity to the applied electric field and the underlying atomic composition of the copper nitride (CuN) monolayer islands grown on a Cu(100) surface. We acquired time-resolved images of THz rectification of H over CuN islands for variable pump-probe delay times to visualize the heterogeneity of the chemical environment at sub-angstrom scale.
扫描隧道显微镜（STM）与泵浦探测飞秒太赫兹（THz）激光相结合，可以实现单个分子的相干测量。我们报告了 THz 泵浦探测测量结果，这些结果基于在 STM 尖端附近的表面上创建的腔中的氢（H）分子，证明了基于量子的传感。从这种量子相干中获得了原子级的空间和飞秒级的时间分辨率。H 分子作为一个两能级系统，其相干叠加对所施加的电场和在 Cu(100)表面上生长的铜氮化物（CuN）单层岛的底层原子组成表现出极端的敏感性。我们获得了 H 在 CuN 岛上的 THz 整流的时间分辨图像，用于不同的泵浦探测延迟时间，以在亚埃尺度上可视化化学环境的非均质性。
