Investigating the influence of conical intersections on the opto-electronic properties of solid-state defects used for novel types of quantum technologies.

金刚石和碳化硅等材料中的固态缺陷，它们最著名的例子是金刚石中的氮空位中心，已经成为利用量子效应在量子信息和量子密码学以及纳米级磁场和温度传感器中的各种应用的流行场所，生物标记物和单光子发射器。本文提出的工作着手研究所谓的锥形交叉对特定光信号的影响。电子性质的三个突出的缺陷，通过使用超快光谱技术，即实验利用飞秒激光脉冲。锥形交叉是分子中的常见现象，并且已知是导致异常快速的光化学反应的原因。这种锥形交叉也可以存在于缺陷中，但它们对缺陷性质的影响迄今被忽视。其基本概念遵循跨学科的方法，通过将分子光谱学中常用的实验技术引入固态缺陷领域，以研究锥形交叉影响的电子和振动动力学。实验方法包括瞬态吸收光谱、飞秒受激拉曼光谱和二维相干光谱。

Solid-state defects in materials such as diamond and silicon carbide, their most famous example being the nitrogen-vacancy centre in diamond, have become a popular playground to harness quantum effects for a variety of applications in quantum information and quantum cryptography, as well as nanoscale magnetic field and temperature sensors, biological markers and single-photon emitters.The herein proposed work sets out to investigate the influence of so-called conical intersections on specific opto-electronic properties of three prominent defects by using ultrafast spectroscopic techniques, i.e. experiments utilising femtosecond laser pulses. Conical intersections are a common phenomenon in molecules and are known to be responsible for exceptionally fast photochemical reactions. Such conical intersections can also exist in defects, yet their impact on defect properties have so far been neglected.The underlying concept follows an interdisciplinary approach by introducing experimental techniques commonly applied in molecular spectroscopy to the field of solid-state defects, in order to study electronic and vibrational dynamics that are influenced by conical intersections. The experimental methods include transient absorption spectroscopy, femtosecond stimulated Raman spectroscopy and two-dimensional coherent spectroscopy.