基于金刚石NV色心的单分子电子-振动耦合效应探测及其应用研究

Vibronic interaction is a very important coupling mechanism in condensed matter physics and structural chemistry. Since the signal provided by the single-molecule’s vibronic coupling is extremely weak, the conventional magnetic resonance technique can only obtain the average properties of the macrocosm (hundreds of millions of samples) and thus can not observe the vibronic coupling at single-molecule level. In view of the excellent sensitivity of nitrogen-vacancy (NV) color center in diamond, this project aims to study the detection of single-molecule’s vibronic coupling effect by NV color center and its applications. The main research work includes proposing a theoretical scheme of real-time detection of the vibronic coupling effect of the single molecule in the inner surrounding environment by using the NV color center. Then we will show how to detecting rotational vibronic coupling effect of external molecule. Based on these, a scheme for monitoring the motion of external molecule in real-time by the NV center-based magnetic resonance technology will be proposed. Finally, we will develop a new kind of nano-scale thermometer which is based on the real-time detection of the single-molecule Jahn-Teller effect. Most of the practical factors will be considered in detail, such as the preparation of the sample, the width of microwave pulse, the temperature and the spin relaxation. The results not only provide a direct theoretical basis for experimentally observing the vibronic coupling effect of single molecule, but also offer a new method for accurately measuring the temperature and detecting the motion of single molecule, which might help people to understand and explore the mechanisms of life and material science at single-molecule level.

电子-振动相互作用是凝聚态物理和结构化学中一种非常重要的耦合机制。因为单个分子的电子-振动耦合效应所提供的信号极其微弱，传统的磁共振技术无法观测到单分子的电子-振动耦合效应。鉴于金刚石NV色心灵敏的探测能力，本项目拟研究NV色心在探测单分子层次的电子-振动耦合效应方面的应用。提出一种利用NV色心探测金刚石内部单分子电子-振动耦合效应的理论方案；并推广到金刚石外部单分子转动电子-振动耦合效应的探测；在此基础上开发一种利用NV色心实时探测单分子运动的新技术；探索基于单分子动态Jahn-Teller效应的监测来实现温度灵敏探测的新方法；所有方案都将充分考虑样品制备、脉冲宽度、环境温度和自旋驰豫等因素的影响。本项目的研究结果不仅有望为实验观察单分子电子-振动耦合效应提供直接的理论依据，也有望为量子精密测量和探测单分子运动提供新思路，有助于人们从单分子层次认知和探索生命和物质科学的机理。

金刚石氮空位中心系统具有良好的稳定性和生物兼容性，其基态哈密顿量中包含了丰富的物理探测资源。本项目发展了基于单个金刚石氮空位中心系统的量子精密测量技术，提出了基于时变脉冲波形的自旋读出序列方法提高金刚石氮空位中心的电子自旋读出效率的可行方案；利用单个金刚石氮空位中心实现了对周围环境自旋中的电子振动耦合效应的实时观测；将周期性量子控制与自适应技术相结合，构建了一种能提高检测弱耦合量子物体的精度的自适应周期调控方法。此外，还研究了远程量子精密测量的精度与噪声之间的关系，提出了利用弱测量及环境辅助测量技术增强远程量子精密测量精度，完美恢复原来的量子Fisher信息的理论方案,使得远程量子参数估计的精度免于振幅阻尼噪声的干扰。最后，研究了关联噪声下的量子密集编码问题，揭示了关联振幅阻尼噪声对量子密集编码容量的影响，提出了利用弱测量及环境辅助测量技术增强密集编码容量的方法。充分展示了弱测量量子反馈控制技术在量子信息处理中的强大应用前景。项目的研究取得一些具有创新性的研究成果，在国内外高级学术刊物发表SCI论文4篇。项目负责人参加国内外学术会议6次，作学术报告2次，获省自然科学奖一项，培养研究生2名。项目的研究成果一方面为实验观察单分子电子-振动耦合效应提供直接的理论依据，有助于人们从单分子层次认知和探索生命和物质科学的机理。另一方面也为远程量子精密测量和量子调控提供新思路。