Preparation of spin squeezed state in SiV centers coupled by diamond waveguide

Spin squeezing is a fascinating manifestation of many-particle entanglement and one of the most promising quantum resources. In this paper, we propose a novel realization of a solid-state quantum spin squeezing by applying Si V centers embedded in a diamond waveguide with the help of a microwave field. The phenomena about the generation of spin squeezing are analyzed numerically in Markovian environments. Our analysis shows that spin squeezing can be generated with the microwave field's help under some realistic conditions, despite the presence of dephasing and mechanical damping.This solid-state spin squeezing based on Si V centers in diamonds might be applied to magnetometers, interferometry, and other precise measurements.     

Effect of deformation of diamond anvil and sample in diamond anvil cell on the thermal conductivity measurement

Studies show that the sample thickness is an important parameter in investigating the thermal transport properties of materials under high-temperature and high-pressure (HTHP) in the diamond anvil cell (DAC) device. However, it is an enormous challenge to measure the sample thickness accurately in the DAC under severe working conditions. In conventional methods, the influence of diamond anvil deformation on the measuring accuracy is ignored. For a high-temperature anvil, the mechanical state of the diamond anvil becomes complex and is different from that under the static condition. At high temperature, the deformation of anvil and sample would be aggravated. In the present study, the finite volume method is applied to simulate the heat transfer mechanism of stable heating DAC through coupling three radiative-conductive heat transfer mechanisms in a high-pressure environment. When the temperature field of the main components is known in DAC, the thermal stress field can be analyzed numerically by the finite element method. The obtained results show that the deformation of anvil will lead to the obvious radial gradient distribution of the sample thickness. If the top and bottom surfaces of the sample are approximated to be flat, it will be fatal to the study of the heat transport properties of the material. Therefore, we study the temperature distribution and thermal conductivity of the sample in the DAC by thermal-solid coupling method under high pressure and stable heating condition.     

Formation on Growth Twins on Mutual Contact of Diamond Crystals

In the course of experimental modeling of diamond crystallization, the phenomenon of crystal twinning in the case of their mutual contact was found. The twinning probability comes up to about 50%, essentially surpassing that on the contact with the walls of the crystallization �hamber (2%).     

蒙特卡罗模拟金刚石薄膜化学气相沉积过程中甲烷浓度的影响

本工作采用蒙特卡罗模拟,研究了以CH4/H2气体混合物作为源料气体的电子辅助热丝化学气相沉积中甲烷浓度对气相沉积过程的影响.计算了典型实验条件下电子能量分布,研究了电子平均能量、碎片H及CH3数目的空间分布、H与CH3的比值及CH3携带的能量随甲烷浓度的变化.结果表明:当电子能量为2-3eV时,电子的数密度达到一峰值;平均电子能量随着甲烷浓度的增加而增加;电子与气体分子碰撞产生的碎片H、CH3和CH2的数密度随距热丝的距离而变化;随着甲烷浓度的增加,原子氢H的数目缓慢下降,然而,官能团CH3和CH2的数目缓慢上升;H与CH3的数量比随甲烷浓度的增加而减少;碎片CH3携带的能量处于1～5eV范围之内,且当甲烷浓度为1.3;时,该能量达到一最值.     

超高压下熔媒法人造金刚石合成机制研究的重要进展

本文对熔媒法人造金刚石的实验、观察和分析,包括熔媒金属(FC或m)、石墨(g)和金刚石(D)存在状态、结晶状况、微观结构和结构特征及其各自结果的分析讨论等研究作了报导.在此基础上对人造金刚石的合成机制作出有机统一整体的讨论如下:(1)形成D结晶基元相变必要条件的特征,可以认为在m熔化过程中发生的助熔激发效应.由于m的d带空穴同g的π-电子相互作用产生各种集团和原子,特别是具有近程有序与密排面结构的原子集团,从而形成一种具有适当尺寸和可变组元的类填隙式固溶体-复合原子集团;(2)形成D结晶基元相变充分条件的特征,可以认为在前述的复合原子集团中的密排面间隙部位发生m的催化激发效应.由于m的价电子处于激发态统计权重增高达到d3s或类sp3状态,诱发处于复合原子集团中类g原子集团实现sp2转移sp3状态.形成一种具有可变组分、不稳定的或部分稳定的类间隙相.这种间隙相式复合原子集团是相变的产物,也是在非平衡态下具有扩散性的主要结晶基底和结晶基元;(3)人造金刚石体系中m/g相互作用的必要和充分条件的特征可用它们的界面结合特征方程作判据来描述.这种判据取决于反映在它们表面和界面上几何结构、电子结构和尺寸等效应(与原子-分子层次结构及相互作用状态有关)的表面能、界面能和有效尺寸.所推导的方程对人造金刚石体系中相互作用,即熔媒激发复合效应的最适合状态提供重要的科学依据和有效技术途径.     

Ab initio calculation of dynamic polarizability and dielectric constant of carbon and silicon cubic crystals

Valence and conduction bands of carbon silicon cubic systems are first obtained by a process called linear combination of atomic orbitals self-consistent field (LCAO-SCF), both at the Hartree-Fock (HF) and local density approximation (LDA) levels. Then, the crystalline orbitals are used in a sum-over-states (SOS) method to calculate the corresponding dielectric constants related to electronic polarizabilities. This method allows parallel computations with large granularity of the optical properties and leads to uncoupled HF and LDA results. © 1997 John Wiley & Sons, Inc. J Comput Chem 18: 1253–1263, 1997     

Igepal CO系列表面活性剂溶致液晶的结构特性

对壬基酚聚氧乙烯醚（IgepalCO）系列表面活性剂,生成何种溶致液晶与其EO基团数n有关,而在何浓度范围内生成溶致液晶则与生成溶致液晶的最低水含量及最大水增溶量有关．EO基团数n小于10时,生成层状液晶,n大于10时则生成六角状液晶,层状液晶两亲双层内,水与表面活性剂的最低摩尔比rmin和最高摩尔比rmax随EO基团数n增加分别是非线型增加与线型增加,在IgepalCO520（n＝5）中加入IgepalCO710（n＝10．5）,对层状液晶的生成无显著影响,在IgepalCO710中加入IgepalCO520,则对六角状液晶的生成产生显著影响,出现了六角状液晶向层状液晶的转变。     

Thermodynamic Properties of the Amorphous and Crystalline Modifications of Carbon and the Metastable Synthesis of Diamond

The temperature dependencies of the thermodynamic properties of the little known (or even hypothetical) undercooled carbon melt and of the glasses that could be obtained from it at appropriate cooling rates are constructed. This is done using both a general thermodynamic formalism to estimate equilibrium properties of undercooled glass‐forming melts and the expected analogy in properties of Fourth Group Elements. A comparison of the hypothetical carbon glasses with amorphous materials, obtained by the pyrolisis of organic resins, usually called vitreous (or glassy) carbon, is made. It turns out that from a thermodynamic point of view existing vitreous carbon materials, although characterized by an amorphous, frozen‐ in structure, differ significantly from the carbon glasses, which could be obtained by a splat‐ cool‐quench of the carbon melt. It is shown also that the hypothetical carbon glasses should have at any temperature a thermodynamic potential, significantly higher than that of diamond. Thus they could be used as a source of constant supersaturation in metastable diamond synthesis. Existing amorphous carbon materials, although showing considerably lower thermodynamic potentials than the hypothetical carbon glasses, could also be used as sources of constant supersaturation in a process of isothermal diamond synthesis if their thermodynamic potential is additionally increased (e.g. by mechano‐ chemical treatment or by dispersion into nano‐size scale). Theoretical estimates made in terms of Ostwald's Rule of Stages indicate that in processes of metastable isothermal diamond synthesis additional kinetic factors (e.g. influencing the formation of sp³ ‐ carbon structures in the ambient phase) and the introduction of active substrates (e.g. diamond powder) are to be of significance in the realization of this thermodynamic possibility.     

CH基团与金刚石(111)面的碰撞反应及其对碳膜生长的影响

等离子体增强化学气相沉积技术中的碳膜选择性自组装机理是高性能碳膜制备过程中的挑战性基础课题.采用经典分子动力学方法,模拟了不同能量(1.625-65 eV)的CH基团在清洁金刚石和吸氢金刚石(111)面上的轰击行为,获得了吸附、反弹、反应等各类事件的发生概率,并据此探讨了含氢碳膜制备过程中CH基团的贡献.结果表明,随着入射能量的增加,CH基团对薄膜生长的贡献由单纯的吸附、反弹机理向反应、吸附混合机理转变,其中最主要的反应过程是释放一个或两个氢原子的反应,而释放氢分子的反应则很少发生.这些反应不仅使薄膜生长过程更均匀、薄膜表面更平整,还降低了薄膜的氢含量.生长机理的转变导致低能量条件下所成薄膜中的多数碳原子都包含一个氢原子作为配位原子,而高能量条件下的薄膜中的碳原子则很少有氢原子作为配位原子.另外,通过分析sp~3-C和sp~2-C数目的变化,研究了CH基团对金刚石基底的破坏作用.     

酪氨酸酶在硼掺杂金刚石薄膜电极上的固定及酚类化合物的检测

以硼掺杂金刚石(boron-doped d iamond,BDD)薄膜作基底,利用光化学反应将含有碳碳双键的烯丙胺化合物修饰在BDD表面,形成氨基单分子层,再经过酰胺键的连接使酪氨酸酶固定在氨基化的金刚石表面,从而制得酪氨酸酶修饰的电极.应用循环伏安法研究该电极用于酚类化合物(包括苯酚、对甲基苯酚和对苯二酚等)检测的灵敏度、线性范围及其稳定性.