近日，美国加州理工学院的Ryan G. Hadt及其研究团队取得一项新进展。经过不懈努力，他们揭示了室温水溶液中分子电子自旋的超快全光相干性。相关研究成果已于2024年11月7日在国际权威学术期刊《科学》上发表。

该研究团队利用泵浦-探测偏振光谱技术，来初始化和追踪分子中的电子自旋相干性。通过设计使自旋与光高效耦合，水溶性的K₂IrCl₆能够在室温及微摩尔浓度下，检测到持续数皮秒的自由感应衰减信号。研究发现，溶液的黏度会显著影响相干寿命。

这种方法将实验的时间分辨率提高了多达五个数量级，使得在传统技术下仅在25K以下才表现出相干性的体系中，也能观察到分子电子自旋相干性。

据悉，顺磁分子的可调性和空间精准性，使其在量子传感领域颇具吸引力。然而，常规的基于微波的检测方法，在时间和空间分辨率上表现不佳，而能与室温溶液兼容的光学方法也一直难以实现。

附：英文原文

Title: Ultrafast all-optical coherence of molecular electron spins in room-temperature water solution

Author: Erica Sutcliffe, Nathanael P. Kazmierczak, Ryan G. Hadt

Issue&Volume: 2024-11-07

Abstract: The tunability and spatial precision of paramagnetic molecules makes them attractive for quantum sensing. However, usual microwave-based detection methods have poor temporal and spatial resolution, and optical methods compatible with room-temperature solutions have remained elusive. Here, we utilized pump-probe polarization spectroscopy to initialize and track electron spin coherence in a molecule. Designed to efficiently couple spins to light, aqueous K₂IrCl₆ enabled detection of few-picosecond free induction decay at room temperature and micromolar concentrations. Viscosity was found to strongly vary decoherence lifetimes. This approach has improved the experimental time-resolution by up to five orders of magnitude, making it possible to observe molecular electron spin coherence in a system that only exhibits coherence below 25 K with traditional techniques.

DOI: 10.1126/science.ads051

Source: https://www.science.org/doi/10.1126/science.ads0512