表面单分子量子态的探测和调控研究进展

Advances in detection and regulation of surface-supported molecular quantum states

单分子体系是一种典型的受限量子体系,且由于其能级分立、轨道局域、化学拓展性强,因而具有丰富的电子态、光子态以及自旋态,这些分子体系中由量子力学决定的物态使得利用单分子作为未来量子信息的载体成为可能.对单分子尺度量子态的探测和调控研究有利于我们“自下而上”精确构建量子器件.由于单分子体系的尺寸限制,宏观的表征手段难以对其进行精确地调控和探测.扫描隧道显微镜具有高精度的实空间定位能力,高分辨的成像和谱学能力,可以实施原位的分子操纵,还可以与多种外场和局域场表征技术联用,是目前精确探测和调控分子尺度量子态特性的重要工具.本文撷取这一领域较为代表性的进展,介绍了基于扫描隧道显微学技术的表面吸附单分子及其相关结构中的量子态研究现状.首先介绍了表面单分子体系量子态的制备手段,然后分别重点介绍了单分子的局域磁自旋态以及单分子作为单光子源的光学特性.对于石墨烯分子结构我们将其视为一种大分子的单分子体系,分别从其拓扑电子态和自旋态的表征和调控两方面做了介绍.最后总结并对单分子量子态研究未来的发展做了展望.

Single molecular systems are typical quantum confinement systems,which have rich electronic states,photon states and spin states due to their discrete energy levels,localized orbitals and diverse chemical structures.The states determined by quantum mechanics in these molecular systems make it possible to serve as great physical entities for future quantum information technology.The detection and manipulation of quantum states on a single molecule scale are beneficial to the bottom-up construction of quantum devices.Owing to the highly limited spatial localization of single molecular systems,it is difficult to accurately address and manipulate them with conventional macroscopic characterization methods.Scanning tunneling microscope(STM)is such a powerful tool that it can achieve high-resolution real-space imaging as well as spectroscopic investigation,with the ability to in-situ manipulating the individual atoms or molecules.It can also work jointly with various near-field or external field characterization techniques,making it a most important technique for precisely detecting and manipulating quantum properties at a single molecule level.In this paper,we review recent research progress of quantum states of surface-supported single molecules and relevant structures based on scanning tunneling microscopy.We start from the methods for the synthesis of molecular structures with desired quantum states,and then we review the recent advances in the local spin states for single molecular systems and the optical properties of single molecules serving as a single-photon source.An emerging family of molecular nanographene systems showing intriguing topological properties and magnetic properties is also reviewed.In the last part,we summarize the research progress made recently and prospect the future development of the quantum states at a single molecular level.