金刚石中NV色心的偶极耦合理论研究

发布时间：2018-04-01 02:37

本文选题：金刚石　切入点：NV色心　出处：《中国科学技术大学》2015年博士论文

【摘要】：金刚石中带负电的氮-空位发光缺陷(NV色心)发光强度高,荧光稳定,同时在室温下它的白旋态有很长的相干时间,可以被微波精确操控。这使得NV色心是一种优秀的发光缺陷,可以用于量子光学和分子能量传递动力学的研究；也是一种优秀的室温量子系统,在量子物理、量子信息、高精度测量和生物标记探测等多个领域都开始有实际应用。随着信息爆炸和技术进步,人们对信息处理的速度要求越来越高。传统的电子集成芯片随着集成度的提高,已经受电子的量子效应、电路的集成工艺、散热等物理极限的制约,无法延续摩尔定律。量子信息是人们发展的未来信息技术,基于量子物理的理论,在信息的获取、传输,尤其是并行处理速度上,有着无可比拟的前景。各种用于实现量子处理器芯片的技术被研究,其中固态体系,尤其是金刚石中的NV色心,是最有竞争力的平台之一。目前,基于NV色心的量子态单比特操作主要依靠微波脉冲实现。微波脉冲的波长在厘米量级,而激光的波长在微米以下。编码在NV色心光学能级上的量子比特同样可以实现单比特操作和基于电偶极耦合的双比特逻辑门。光学操控的量子比特除了有自旋比特的可扩展性,还具有集成性,更适于用作量子处理器芯片。而作为晶体中的缺陷,NV的能级相对复杂,偶极和跃迁过程丰富多样,其耦合机制和动力学尚不明晰。为了理解NV色心偶极耦合的动力学以便更好地应用,我们进行了如下的理论研究： 1.回顾和描述了单个NV色心的能级结构。我们用广泛采用的对称性分析方法分析了它的能级结构,回顾了目前较为公认的能级模型,并仔细描述了电场、应变和磁场等对能级的调节。对能级的调节使得不同的NV色心能够能级共振,是在实验上不可缺少的技术。 2.详细计算了电偶极耦合的NV色心的动力学过程。NV色心是一个多能级结构的缺陷,电偶极的耦合可以具有不同的情况。我们用量子电动力学的方法写出了两个NV依靠电偶极耦合的主方程,详细计算了NV里面线性偶极耦合、圆偏振偶极耦合、线偏振和圆偏振耦合时系统的动力学过程。这些过程对于量子体系里的能量传输,基于电偶极耦合的量子器件等研究都提供了参考。我们还提出了基于电偶极耦合的应用,包括超分辨成像中纵向距离的校准、非局域的自旋翻转操控等。 3.详细了研究了通过金属表面的表面等离子体增强偶极耦合的方案。实验上通过离子注入产生的NV色心阵列分布在金刚石表面,镀上金属薄膜作为波导即可增强它们的耦合。我们回顾了当介质非均匀、有色散和吸收时,计算两个偶极耦合强度的格林函数方法,并用它计算了NV色心受到金刚石界面、金属平面波导影响时寿命和耦合强度的变化,尤其是随着NV色心深度、金属薄膜厚度的变化。这种方案使得NV色心在光学波长的距离上能够有效耦合。本文的内容安排为：第一章介绍NV的研究背景、现状和研究偶极耦合的NV色心的动机；第二章,将基于对称性分析回顾NV色心的能级结构,并详细描述各种外场对能级的调节；第三章,通过主方程方法详细计算两个NV的耦合动力学及其应用；第四章,回顾非均匀介质中偶极耦合强度的计算方法,计算界面对NV耦合的影响；第五章,详细计算金属薄膜增强了的NV色心的耦合；第六章,介绍一个利用固态自旋耦合制备纠缠态,并用于磁场测量的应用；第七章对全文的工作做了总结,并对尚未解决的问题作了回顾,对未来的工作提出展望。 NV色心作为固体中一种典型的缺陷,这些理论对于固体中的其它缺陷的耦合研究也有参考作用。研究NV色心的光学过程还可以更好的控制其中的自旋动力学,和NV的自旋系统结合,发挥各自的优点。因此,NV色心的光学过程和电偶极耦合会在量子信息里有重要应用。未来我们将进一步考虑增强了的偶极耦合在量子信息中如何更好的应用,以及在有声子等的环境中,如何通过有效的电偶极耦合制备量子器件。
[Abstract]:The N - vacancy luminescent defect ( NV color center ) with negative electrode in diamond has high luminous intensity and stable fluorescence , while at the same time it has a long coherence time at room temperature . It can be precisely controlled by microwave . This makes the NV color center a good light - emitting defect , which can be used for the research of quantum optics and molecular energy transfer dynamics .
The invention is also an excellent room temperature quantum system , and has practical application in various fields such as quantum physics , quantum information , high - precision measurement and biological marking detection .

With the improvement of information explosion and technology , the speed requirement of information processing is becoming higher and higher . The traditional electronic integrated chip has been limited by the physical limit of quantum effect , integrated process and heat dissipation of the electronic , and it can not extend Moore ' s Law . The quantum information is the future information technology of people .

The quantum bit operation based on the NV color center is mainly realized by microwave pulses . The wavelength of the microwave pulse is in the order of centimeters , and the wavelength of the laser is less than microns . The quantum bit encoded on the optical energy level of the NV color center can also realize the single bit operation and the double bit logic gate based on the electric dipole coupling . The quantum bit coded on the NV color center optical energy level can also realize the single bit operation and the double bit logic gate based on the electric dipole coupling .

1 . The energy level structure of a single NV color center is reviewed and described . The energy level structure is analyzed by a widely used symmetry analysis method . The energy level model is reviewed . The energy level of the electric field , strain and magnetic field is carefully described . The adjustment of the energy level makes the different NV color centers capable of resonance , which is an indispensable technique in the experiment .

2 . The dynamic process of the NV color center coupled by an electric dipole is calculated in detail . The NV color center is a defect of a multi - level structure , and the coupling of the electric dipole can be different . The dynamics of the system in the NV inner linear dipole coupling , the circular polarization dipole coupling , the linear polarization and the circular polarization coupling are calculated in detail by using the quantum electrodynamics method . The application of the process is based on the coupling of the electric dipole , including the calibration of the longitudinal distance in the super - resolution imaging , the non - local spin inversion control , and the like .

3 . The coupling of the surface plasma enhanced dipole with metal surface is studied in detail . The results show that the NV color center array produced by ion implantation is distributed on the surface of the diamond and the metal thin film can be used as the waveguide to enhance their coupling . We review the change of the lifetime and the coupling strength of the NV color center under the influence of the diamond interface and the metal planar waveguide , especially with the depth of the NV color center and the thickness of the metal film .

The contents of this paper are as follows : The first chapter introduces the research background of NV , the current situation and the motives of researching the NV color center of the dipole coupling .
In chapter 2 , the energy level structure of the NV color center will be reviewed based on the symmetry analysis , and the adjustment of the energy level of various external fields will be described in detail .
In chapter 3 , the coupling dynamics and the application of two NV are calculated in detail through the main equation method .
In chapter 4 , the calculation method of dipole coupling strength in non - uniform medium is reviewed , and the influence of interface on NV coupling is calculated .
In chapter 5 , the coupling of NV color centers enhanced by metal thin film is calculated in detail .
In chapter 6 , an entangled state is prepared by solid - state spin coupling and applied to magnetic field measurement .
Chapter 7 summarizes the work of the full text , and reviews the outstanding issues and looks forward to the future work .

The NV color center is a typical defect in the solid . These theories also have a reference to the coupling of other defects in the solid . The optical process of the NV color center can also better control the spin dynamics and the spin system of the NV . Therefore , the optical process of the NV color center and the coupling of the electric dipole can play an important role in the quantum information . In the future , we will further consider how the enhanced dipole coupling can be better applied in the quantum information , and how to prepare the quantum device through the effective dipole coupling in the environment of the voiced sub or the like .

【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TQ163;O773

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