Ultra-sensitive hybrid diamond nanothermometer

Nitrogen-vacancy (NV) centers in diamond are promising quantum sensors because of their long spin coherence time under ambient conditions. However, their spin resonances are relatively insensitive to non-magnetic parameters such as temperature. A magnetic-nanoparticle-nanodiamond hybrid thermometer, where the temperature change is converted to the magnetic field variation near the Curie temperature, were demonstrated to have enhanced temperature sensitivity () (Wang N, Liu G-Q and Leong W-H et al. Phys Rev X 2018; 8: 011042), but the sensitivity was limited by the large spectral broadening of ensemble spins in nanodiamonds. To overcome this limitation, here we show an improved design of a hybrid nanothermometer using a single NV center in a diamond nanopillar coupled with a single magnetic nanoparticle of copper-nickel alloy, and demonstrate a temperature sensitivity of . This hybrid design enables detection of 2 mK temperature changes with temporal resolution of 5 ms. The ultra-sensitive nanothermometer offers a new tool to investigate thermal processes in nanoscale systems.     

原子尺度的亚稳态金刚石膜的生长、形核和异质外延的机理研究

金刚石由于它在力学、热学、光学及电子学方面极其优异的性能和最近它在低压合成方面的成功,近年来它的研究和开发吸引了很多人,形成了一股热潮。但是也遇到了困难,其中最突出的是,对金刚石膜的生长和形核机理还不很清楚,使得人们不能很好地控制膜的生长和质量,来满足实际应用中的各种要求。其次,大面积的异质外延金刚石单晶膜还未能获得,不能实现金刚石膜在高温、高速、高功率和高集成度电子器件上的应用。碳的平衡相图告诉我们,在低温低压生长条件下石墨是稳定相;而只有在高温高压生长条件下,金刚石才是稳定相。所以在低压下用…     

构建平衡性企业培训评估钻石模型初探

员工培训工作已成为企业发展的战略性要求,在企业人力资源管理中占据着十分重要的地位。但是,如果培训评估工作不甚完善就会影响企业的培训工作。认为对于培训评估应当结合企业自身的实际情况进行平衡性评估分析,从不同的侧面全面衡量培训所带来的各方面变化,并在现有研究理论基础上首次从平衡分析的角度构建了培训评估钻石模型,希望对企业的培训评估工作提供一定的借鉴。     

Experimental measurement of the quantum geometric tensor using coupled qubits in diamond

Geometry and topology are fundamental concepts, which underlie a wide range of fascinating physical phenomena such as topological states of matter and topological defects. In quantum mechanics, the geometry of quantum states is fully captured by the quantum geometric tensor. Using a qubit formed by an NV center in diamond, we perform the first experimental measurement of the complete quantum geometric tensor. Our approach builds on a strong connection between coherent Rabi oscillations upon parametric modulations and the quantum geometry of the underlying states. We then apply our method to a system of two interacting qubits, by exploiting the coupling between the NV center spin and a neighboring ¹³C nuclear spin. Our results establish coherent dynamical responses as a versatile probe for quantum geometry, and they pave the way for the detection of novel topological phenomena in solid state.     

中国设计产业钻石模型的双结构方程检验

运用"双结构方程"新方法,就中国设计产业来验证M E.Porter钻石模型理论框架,以及各因子之间相互影响。运用基于设计产业现实表现评价和基于对设计产业的重要性评价的李克特量表数据,分别构建两个耦合的结构方程模型并比较其结果。研究表明:显示设计产业不存在要素驱动和投资驱动;本文双钻石模型模型中Porter四个决定因子之间存在显著相互作用,在基于重要性评价的模型中相关更为显著;Porter钻石模型能够解释中国设计产业竞争优势,基于重要性评价模型不支持政府作用是设计产业钻石模型的一个决定因子,但Porter的钻石模型的4个决定因子加上政府作用可以解释中国设计产业竞争优势的现实表现。本文证明政府的直接作用从长期来看并不能增强一个产业的竞争优势,设计产业在这一点上与其他产业并无不同。     

纳米金刚石颗粒导热系数的分子动力学研究

应用分子动力学模拟的方法,研究了纳米金刚石颗粒的导热系数对温度和颗粒尺寸的依存关系。为了得到较为准确的模拟结果,采用了平衡态分子动力学模拟的方法。计算了较长时间的热流自相关函数,并得到了导热系数的收敛结果。结果表明,纳米金刚石颗粒由于尺寸的影响,导热系数低于体材料金刚石的导热系数;随温度的升高,导热系数出现一个峰值,该峰值点的温度小于体材料金刚石出现峰值点的温度;随颗粒尺寸的增大,导热系数增加,我们预测导热系数将在一定的颗粒尺寸时收敛于体材料金刚石的导热系数。     

Broadcast diamond channel: Transmission strategies and bounds

This paper proposes a new multiuser communication model in which a source with broadcast capabilities wants to transmit two different messages to two different destinations in the case that no direct links between the source and its destinations. In this channel model, two parallel half-duplex relays are used to extend the transmission. For this communication model, an outer bound to the achievable capacity is initially derived. Then, two distinctive transmission schemes are characterized such that the source can transmit to the two destinations. In each scheme, the transmission is split into two phases. Specifically, in the first phase, the source can broadcast different messages to the two relays. Then, in the second phase, the two relays can forward the source’s signals into their destinations. Based on the transmission on each scheme, the achievable rate region is characterized. Further, we derive the optimal duration of each phase. The theoretical analyses are followed by many numerical examples that compare between the different transmission techniques and also show the points at which the capacity is achieved.     

中国汽车零部件产业的钻石模型分析

零部件产业的竞争优势关系到一国整个汽车工业的发展水平。本文运用波特的钻石模型框架,对我国汽车零部件产业竞争优势的主要影响因素进行了分析,在此基础上给出提高我国汽车零部件产业竞争力的建议。     

On simplified Hurwitz stability conditions for low-degree weighted diamond polynomials

In this paper, the results on the stability of a weighted diamond of polynomials which was studied by Kharitonov and Tempo (Systems Control Lett. 22 (1994)) are simplified for low-order polynomials. Specifically, for n=3 and 4, the number of polynomials required to check the stability is four and six, respectively, instead of eight. Further, diamond of polynomials which were studied by Barmish et al. (IEEE Trans. Automat. Control AC-37 (9) (1992)) are also investigated.