Engineered electron-phonon interaction of negatively charged Silicon-Vacancy center in nanostructured diamond.

该项目的目的是延长SIV中心的相干性，同时在几个开尔文的中等温度下工作。我们奉行两种战略。1)在纳米金刚石(NDS)中使用SIV中心引入了共振声子模的截止频率。当处理几十纳米尺寸的声子频率时，低于相应精细结构的声子频率将被抑制。这一战略的挑战来自于小尺寸，因此SIV中心靠近钻石表面，导致光不稳定和光谱不稳定。方法包括NDS中SIV中心的化学稳定和生产工艺的改进。2)由于自旋弛豫源于与具有E点群对称性的声子模的相互作用，因此在纳米机械谐振器中嵌入SIV中心可以降低可用声子态的密度，并抑制与具有精细结构跃迁共振的E声子模的耦合，从而降低自旋弛豫。与SIV-CENTER相比，NDS的主要优势是增加了结构尺寸。发射体离钻石表面更远，从而产生块状光学特性。这一策略的主要挑战来自于专用的金刚石纳米结构和各种几何形状的纳米柱结构的制造，以及声子模式中SIV中心的定位。通过这个项目，我们建立了一种新的量子发射体，在中等温度下具有良好的光学性能和长的相干时间，在量子中继器、量子传感或量子信息方面具有潜在的应用前景。

The aim of the project is to prolong coherence properties of SiV-center while operating at moderate temperatures of few Kelvin. We pursue two strategies. 1) Employing SiV- center in nanodiamonds (NDs) introduces a cut-off frequency for resonant phonon modes. When working with sizes of a few tens of nanometers phonon frequencies below the relevant fine structure transition will be suppressed. Challenges for this strategy arise from the small size and therefore the proximity of the SiV-center to the diamond surface resulting in photo-instability and spectral-instability. Methods include chemical stabilization of SiV-center in NDs and improvements in ND production process. 2) Since spin relaxation originates from interaction with phonon modes of E point-group symmetry the spin relaxation can be reduced by embedding SiV-centers in nano-mechanical resonators where density of available phonon states is reduced and coupling to E phonon modes that are resonant with fine structure transitions is suppressed. Main advantage compared to SiV- center in NDs is the increased structure size. The emitters are further away from the diamond surface resulting in bulk-like optical properties. Main challenges of this strategy arise from dedicated diamond nano-structuring and fabrication of nano-pillar structures (NPs) of various geometry as well as positioning of SiV-center within phononic mode. With this project, we establish a new quantum emitter with excellent optical properties and long coherence times at moderate temperatures with potential applications in Quantum repeaters, Quantum sensing, or Quantum Information.