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All Results

A new approach to characterize the violation of Lorentz invariance

胡锦文Subjects: Physics >> Geophysics, Astronomy, and Astrophysics

本文引入了一个参量n来表征不同惯性系间光速的变化。为了满足众所周知的基本原理，又不违背一些可靠的实验结果，我们应该对n施加一些必要的约束。首先，重要的是，n的引入应该符合以下三个原则:(1)我们可以用一个规定的时钟同步来定义整个空间中的时间;(2)时间是均匀的，空间是各向同性的;(3)所有的惯性系统都是等价的，这是对狭义相对论(SR)思想的继承。在n的一些约束条件下，我们构造了一个满足惯性系对称性的一般坐标变换。近年来，许多理论都表现出对超高能量尺度下洛伦兹不变性的破坏的兴趣，例如量子引力，它暗示粒子的能量有一个有限值(称为普朗克能量)，而不是从洛伦兹模型导出的无限值。因此我们构造一个n的表达式来描述洛伦兹模型的违逆。进一步，通过与著名的彩虹模型比较，我们发现本文推导的“最大能量”与彩虹模型假设的“最大能量”有一定的关系。 |

submitted time
2021-02-25
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Development of X-ray spectrometer automatic adjustment system based on global optimization algorithm

Fei ZhanSubjects: Physics >> Nuclear Physics

In high energy resolution X-ray spectroscopy beamlines of synchrotron radiation (SR) facilities and laboratory XAS/XES spectrometer, it is important to keep X-ray spectrometer operating in optimal conditions. The adjusting process is normally very time consuming due to the irregular light source beam point, and it is difficult to get global optimum. This study aims to develop an intelligent adjusting system based on global optimization algorithm for spectrometers on SR beamlines and on laboratory x-ray source. First of all, based on the two dimensional experimental data, automatic adjustment process was established. Then the automatic optimization was applied to adjust X-ray spectrometer practically, and upgraded iteratively. The online testing is carried out on a self-developed laboratory XAS spectrometer. Online tests results show that this automatic adjustment process converges to the optimal solution quickly, and the convergence time is about several dozens to hundreds steps, more efficient than manual optimization process. After automatic adjustment, we can get correct X-ray absorption spectrum based on the adjusted spectrometer. |

Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

本文从符号与信息的角度，对混沌动力系统的特性进行了分析。提出了基于集合划分的信息熵传递特性，对连续动力系统引入有限测量精度假设，由此得出形成混沌的两个必要机制：信息由小尺度向宏观大尺度的转移及宏观信息的不断耗散，并进而对物理系统中的信息耗散进行分析讨论。 |

Quantum entanglement measurement based on belief entropy

Xue, Yige; Deng, YongSubjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Partial entropy entanglement is a very popular method to measure the entanglement of quantum systems, which is based on the classic von Neumann entropy. However, because of the problem of classical von Neumann entropy in measuring the uncertainty of quantum systems, the partial entropy entanglement is not efficient enough to measure the entanglement of quantum systems. The new entropy measure of quantum uncertainty is a model for measuring the uncertainty of a quantum system based on the classic von Neumann entropy and belief entropy, which has higher performance than the classic von Neumann entropy in measuring the uncertainty entropy of a quantum system.Based on the new entropy measure of quantum uncertainty and the classic partial entropy entanglement, this paper proposes a new model to measure the quantum entanglement measurement, named quantum entanglement measurement based on belief entropy. When the new entropy measure of quantum uncertainty degenerates to classical von Neumann entropy, the quantum entanglement measurement based on belief entropy will degenerate to classical partial entropy entanglement. Numerical examples are used to prove that quantum entanglement measurement based on belief entropy is more efficient and reliable in measuring the entanglement of quantum systems than the classic partial entropy entanglement. The experimental results show that the quantum entanglement measurement based on belief entropy can measure the uncertainty of quantum systems more efficiently and reliably than the classical classic partial entropy entanglement. |

A new entropy measure of quantum system uncertainty

Yige Xue; Yong DengSubjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Quantum theory is currently the most important research field. Before processing the information of a quantum system, we must first understand how to measure the uncertainty of a quantum system. Von Neumann entropy is a very classic method to measure the uncertainty of quantum systems. However, due to the particularity of quantum systems, it is very difficult to measure the uncertainty of quantum systems, so that the measurement efficiency of the classical von Neumann entropy is not high in some cases. Based on the classic von Neumann entropy and belief entropy, this paper proposes a new entropy model to measure the uncertainty of quantum systems, which can use fully the eigenvalues and eigenvectors of the density matrix of quantum systems, and give the uncertainty of the quantum system. Some numerical examples are used to prove that the proposed entropy is more efficient and reliable in measuring quantum systems than the classical von Neumann entropy. The experimental results show that the proposed entropy can measure the uncertainty of quantum systems more efficiently and reliably than the classical von Neumann entropy. |

Subjects: Physics >> Condensed Matter: Electronic Structure, Electrical, Magnetic, and Optical Properties

The past decade has witnessed a surge of interest in exploring emergent particles in condensed matter systems. Novel particles, emerged as excitations around exotic band degeneracy points, continue to be reported in real materials and artificially engineered systems, but so far, we do not have a complete picture on all possible types of particles that can be achieved. Here, via systematic symmetry analysis and modeling, we accomplish a complete list of all possible particles in time reversal-invariant systems. This includes both spinful particles such as electron quasiparticles in solids, and spinless particles such as phonons or even excitations in electric-circuit and mechanical networks. We establish detailed correspondence between the particle, the symmetry condition, the effective model, and the topological character. This obtained encyclopedia concludes the search for novel emergent particles and provides concrete guidance to achieve them in physical systems. |

A new Lorentz violating model with particle’s "maximum energy"

胡锦文Subjects: Physics >> Geophysics, Astronomy, and Astrophysics

在Lorentz破缺模型中，通常会讨论彩虹模型，因为彩虹模型可以使粒子的能量具有极限而不是与Lorentz变换相对应的具有无限值，而这在量子引力中被认为是必需的。然而，本文表明，当我们只是坚持时空是均匀的，空间是各向同性的并且所有惯性系统都是等价时，并没有必要将光速限制为常数。并且由于光速的变化，我们可以完全构造惯性系统的坐标变换，使粒子的能量有一个极限，而这与彩虹模型相同。 此外，在最近的论文中，作为超高能量尺度的测试，彩虹模型用于研究伽马射线爆，例如GRB 160509A事件，该事件强烈暗示光速随其能量变化的线性形式。所以我们也分析了这个事件，发现我们的模型和彩虹模型之间存在联系。最后，我们简要讨论了如何在超高能量级的未来粒子实验中验证这两个模型。 |

submitted time
2021-01-24
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Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Urban topsoil is the most frequent interface between human society and natural environment. The accumulation of heavy metals in the urban topsoil has a direct effect on residents' life and health. The geochemical baseline of heavy metals is an objective description of the general level of heavy metals in the urban topsoil. Meanwhile, the determination of geochemical baseline is necessary for regional environmental management, especially in coal cities prone to heavy metal pollution. Heavy metal pollution has become an environmental problem in Fuxin City, China for a long time. To establish the geochemical baseline of heavy metals in the topsoil of Fuxin City and to evaluate the ecological risk of the topsoil, we collected 75 topsoil samples (0–20 cm) and analyzed the concentrations of Cu, Ni, Zn, Pb, Cr, Cd, Hg and As through X-ray fluorescence spectrometry, atomic absorption spectrometry and inductively coupled plasma optical emission spectrometry. We determined the geochemical baseline of heavy metals in the topsoil of Fuxin City by using iteration removal, box-whisker plot, cumulative frequency curve and reference metal normalization; evaluated the contamination risk and ecological risk of the topsoil by using the baseline factor index, Nemerow index and Hakanson potential ecological risk index; and identified the source category of heavy metals in the topsoil by using a pedigree clustering heatmap. Results showed that the geochemical baseline values were 42.86, 89.34, 92.23, 60.55, 145.21, 0.09, 0.08 and 4.17 mg/kg for Cu, Ni, Zn, Pb, Cr, Cd, Hg and As, respectively. The results of Nemerow index and Hakanson potential ecological risk index indicated that the urban topsoil in the study area was slightly contaminated and suffering low potential ecological risk. The main contaminated areas dominated in the middle part and northeast part of the study area, especially in the western Haizhou Strip Mine. The result of baseline factor index indicated that Hg and Cd were the major pollution elements. Using a pedigree clustering heatmap, we divided the sources of these heavy metals into three types: type I for Ni and Cr, largely represented the enrichment of heavy metals from natural sources; type II for Cu, Pb, Zn, Cd and As, mainly represented the enrichment of heavy metals from anthropogenic sources; and type III for Hg, represented the form of both natural and anthropogenic inputs. |

submitted time
2021-01-15
From cooperative journals:《Journal of Arid Land》
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Subjects: Physics >> The Physics of Elementary Particles and Fields

In this article, first we review the current evidences for the existence of dark matter, and then we examine possible candidates for dark matter. Possible experiments are suggested which might test the nature of dark matter. |

Experimental Observation of Thermal Energies of Helium-4 Superflows

Yu, Yongle; Luo, HailinSubjects: Physics >> Condensed Matter: Electronic Structure, Electrical, Magnetic, and Optical Properties

We observed a counter-intuitive remarkable heating phenomenon generated by helium-4 superflows. This phenomenon establishes that superflows carry thermal energies and entropies, which is in contrast to the hypothesis of the two-fluid model. Quantum many-body theory of superfluids provides a natural understanding of the phenomenon. |