共查询到20条相似文献，搜索用时 0 毫秒
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In this paper, we use the result in [C.Y. Sun and D.H. Zhang, arXivastro-ph/0510709] to calculate the non-Gaussianity of the racetrack models in[J.J. Blanco-Pillado, et al., JHEP 0411 (2004) 063; arXivhep-th/0406230]and [J.J. Blanco-Pillado, et al., arXivhep-th/0603129]. The two models give different non-Gaussianities. Both of them are reasonable. However, we find that, for multi-field inflationary models with the non-trivial metric of the field space,the condition of the slow-roll cannot guarantee small non-Gaussianities. 相似文献
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In this paper, we present a gauge inflation model based on the orbifold M_4×S~1/Z_2 with non-Abelian SU(2) gauge symmetry, which is probably the simplest model in this category. As the inflaton potential is fully radiatively generated exclusively by gauge self-interactions, the model is predictive; thus, it is protected by gauge symmetry itself, without the introduction of any additional matter fields or arbitrary interactions. We show that the model fully agrees with the recent cosmological observations within the controlled perturbative regime of gauge interactions, g4≤1/(2πRMP), with the compactification radius(10 ≤ RMP ≤ 100): the expected magnitude of the curvature perturbation power spectrum and the value of the corresponding spectral index are in perfect agreement with the recent observations. The model also predicts a large fraction of the gravitational waves, negligible nonGaussianity, and a sufficiently high reheating temperature. 相似文献
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We review the theory of inflationary perturbations. Perturbations at both linear and nonlinear orders are reviewed. We also review a variety of inflation models, emphasizing their signatures on cosmic perturbations. 相似文献
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Zahra Koohi Lai Ali Namaki Ali Hosseiny Gholamreza Jafari Marcel Ausloos 《Entropy (Basel, Switzerland)》2021,23(1)
In this paper, we focus on the critical periods in the economy that are characterized by unusual and large fluctuations in macroeconomic indicators, like those measuring inflation and unemployment. We analyze U.S. data for 70 years from 1948 until 2018. To capture their fluctuation essence, we concentrate on the non-Gaussianity of their distributions. We investigate how the non-Gaussianity of these variables affects the coupling structure of them. We distinguish “regular” from “rare” events, in calculating the correlation coefficient, emphasizing that both cases might lead to a different response of the economy. Through the “multifractal random wall” model, one can see that the non-Gaussianity depends on time scales. The non-Gaussianity of unemployment is noticeable only for periods shorter than one year; for longer periods, the fluctuation distribution tends to a Gaussian behavior. In contrast, the non-Gaussianities of inflation fluctuations persist for all time scales. We observe through the “bivariate multifractal random walk” that despite the inflation features, the non-Gaussianity of the coupled structure is finite for scales less than one year, drops for periods larger than one year, and becomes small for scales greater than two years. This means that the footprint of the monetary policies intentionally influencing the inflation and unemployment couple is observed only for time horizons smaller than two years. Finally, to improve some understanding of the effect of rare events, we calculate high moments of the variables’ increments for various q orders and various time scales. The results show that coupling with high moments sharply increases during crises. 相似文献
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Jiyong Park 《Entropy (Basel, Switzerland)》2022,24(2)
We derive the lower bounds for a non-Gaussianity measure based on quantum relative entropy (QRE). Our approach draws on the observation that the QRE-based non-Gaussianity measure of a single-mode quantum state is lower bounded by a function of the negentropies for quadrature distributions with maximum and minimum variances. We demonstrate that the lower bound can outperform the previously proposed bound by the negentropy of a quadrature distribution. Furthermore, we extend our method to establish lower bounds for the QRE-based non-Gaussianity measure of a multimode quantum state that can be measured by homodyne detection, with or without leveraging a Gaussian unitary operation. Finally, we explore how our lower bound finds application in non-Gaussian entanglement detection. 相似文献
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磁性斯格明子是拓扑稳定的自旋结构,它的尺寸小,驱动电流阈值小,被广泛认为是下一代磁性存储的基本单元.斯格明子的主要优势在于它奇特的动力学性质,特别是它能够与传导电子相互作用,在低电流密度驱动下可以在赛道上稳定地运动.本文结合磁性斯格明子赛道存储的最新研究成果,对斯格明子在赛道上的写入、驱动和读出三个方面进行了较为详细的综述.重点介绍了注入自旋极化电流这一最常见的驱动方法,分析了斯格明子在赛道上的堵塞和湮没现象,探讨了斯格明子霍尔效应及其可能造成信号丢失的危害和相关的解决方法,并在此基础上详细介绍了几种斯格明子塞道存储的优化设计方案.最后总结了磁性斯格明子赛道存储面临的一些挑战. 相似文献
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In order to increase the number of channels that could be multiplexed or demultiplexed in the dense wavelength division multiplexed (DWDM) system based on the resonators on silicon-on-insulator (SOI) technology, the Vernier effect in the series-coupled racetrack resonators is presented to extend the free spectral range (FSR) of the DWDM systems. A method is developed based on a matrix approach to simulate Vernier devices. A three-dimensional full vectorial finite difference (FVFD) model, specifically suited for high index contrast and smaller size waveguides, for example, a waveguide in SOI technology, is developed to obtain the properties of a waveguide. Finally, the Vernier effect in the two series-coupled racetrack resonators is experimentally verified with an improved FSR and interstitial resonance suppression. 相似文献
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Feng Xie Yangbo He Zhi Geng Zhengming Chen Ru Hou Kun Zhang 《Entropy (Basel, Switzerland)》2022,24(4)
This paper investigates the problem of selecting instrumental variables relative to a target causal influence from observational data generated by linear non-Gaussian acyclic causal models in the presence of unmeasured confounders. We propose a necessary condition for detecting variables that cannot serve as instrumental variables. Unlike many existing conditions for continuous variables, i.e., that at least two or more valid instrumental variables are present in the system, our condition is designed with a single instrumental variable. We then characterize the graphical implications of our condition in linear non-Gaussian acyclic causal models. Given that the existing graphical criteria for the instrument validity are not directly testable given observational data, we further show whether and how such graphical criteria can be checked by exploiting our condition. Finally, we develop a method to select the set of candidate instrumental variables given observational data. Experimental results on both synthetic and real-world data show the effectiveness of the proposed method. 相似文献
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斯格明子电子学的研究进展 总被引：1，自引：0，他引：1
在过去的半个世纪中,微电子技术一直沿着著名的摩尔定律快速发展,当前已经达到单芯片可集成上百亿晶体管.然而随着晶体管尺寸的缩小,因量子效应所产生的漏电流及其所导致的热效应使得这一定律遇到瓶颈.自旋电子技术由于引入了电子自旋这一全新的自由度,将有望大幅度降低器件功耗,突破热效应枷锁.斯格明子是一种具有拓扑保护的类粒子自旋结构,有望成为下一代自旋电子信息载体,引起了从物理到电子领域的广泛关注.由于其特殊的拓扑性质,斯格明子具备尺寸小、结构稳定、驱动阈值电流小等诸多优点,室温下斯格明子的成核、输运及探测进一步验证了其广泛的应用潜力,由此诞生了研究相关器件及应用的斯格明子电子学.本综述从电子学角度首先介绍斯格明子的基础概念及发展现状、理论及实验研究方法,重点阐述斯格明子器件的写入、调控及读取功能,介绍了一系列具有代表性的新型信息器件;最后,结合斯格明子电子学现状分析了目前所面临的发展瓶颈以及未来的应用前景. 相似文献
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Cheng Xiang 《中国物理 B》2022,31(3):30306-030306
We propose three alternative measures for non-Gaussianity of quantum states: sine distance, Bures angle, and Bures distance, which are based on quantum fidelity introduced by Wang [Phys. Lett. A 373 58 (2008)]. Using them, we evaluate the non-Gaussianity of some relevant single-mode and two-mode non-Gaussian states and find a good consistency of the three examined measures. In addition, we show that such metrics can exactly quantify the degree of Gaussianity of even Schrödinger-cat-like states of small amplitudes that can not be measured by other known non-Gaussianity measures such as the Hilbert—Schmidt metric and the relative entropy metric. We make a comparative study between all existing non-Gaussianity measures according to the metric axioms and point out that the sine distance is the best candidate among them. 相似文献
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In the present paper, an equation of state has been obtained in case of liquid alkali metals like Na, K, Rb and Cs from sound
velocity measurements. The theory developed gives very good agreement for both the sound velocity and the volume as a function
of pressure at different temperatures in these liquid alkali metals. Further, the variation of non-linear parameter,B / A, as a function of pressure and temperature is also studied. 相似文献
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A biological sensing structure with a high-order mode ($mathrm{E}_{21}^{y}$) is designed, which is composed of a suspended racetrack micro-resonator (SRTMR) and a microfluidic channel. The mode characteristics, coupling properties, and sensing performances are simulated by using the finite element method (FEM). To analyze the mode confinement property, the confinement factors in the core and cladding of the suspended waveguide for the $mathrm{E}_{11}^{x}$, $mathrm{E}_{11}^{y}$, and $mathrm{E}_{21}^{y}$ are calculated. The simulation results show that the refractive index (RI) sensitivity of the proposed sensing structure can be improved by using the high-order mode ($mathrm{E}_{21}^{y}$). The RI sensitivity for the $mathrm{E}_{21}^{y}$ mode is ～ 201 nm/RIU, which is twice to thrice higher than those for the $mathrm{E}_{11}^{x}$ mode and the $mathrm{E}_{11}^{y}$ mode. Considering a commercial spectrometer, the proposed sensing structure based on the SRTMR achieves a limit of detection (LOD) of ～ 4.7×10-6 RIU. Combined with the microfluidic channel, the SRTMR can possess wide applications in the clinical diagnostic assays and biochemical detections. 相似文献
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Nan Zhang Ya-Bo Wu Jun-Wang Lu Chu-Wen Sun Li-Jie Shou Hai-Zhou Xu 《中国物理C(英文版)》2020,44(9):095107-095107-8
Based on the dynamics of single scalar field slow-roll inflation and the theory of reheating, we investigate the generalized natural inflationary (GNI) model. We introduce constraints on the scalar spectral index begin{document}$n_{s}$end{document} ![]()
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begin{document}$Lambda$end{document} ![]()
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begin{document}$+r$end{document} ![]()
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begin{document}$n_{s}=0.9659pm0.0044$end{document} ![]()
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begin{document}$r<0.0623$end{document} ![]()
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begin{document}$log_{10}(f/M_{p})= 0.62^{+0.17}_{-0.18}$end{document} ![]()
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begin{document}$m=0.35^{+0.13}_{-0.23}$end{document} ![]()
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基于n型金属氧化物半导体场效应晶体管（nMOSFET）噪声的数涨落模型,采用高阶统计量双相干系数平方和研究了nMOSFET噪声的非高斯性.通过对nMOSFET实际测试噪声的分析,发现nMOSFET器件噪声存在非高斯性;小尺寸器件噪声的非高斯性强于大尺寸器件;在器件的强反型线性区,其非高斯性随着漏压的增加而增加.文中还通过蒙特卡罗模拟和中心极限定理理论对nMOSFET噪声的非高斯性作了深入的探讨.关键词：噪声非高斯性n型金属氧化物半导体场效应晶体管氧化层陷阱 相似文献