Frontiers of Physics

ISSN 2095-0462

ISSN 2095-0470(Online)

CN 11-5994/O4

2018 Impact Factor: 2.483

Perovskite oxides thin films exhibit diverse properties and are of prime importance to multi-functional integrated electronic devices, where a burst of strategies are proposed to manipulate their intimate couplings and uncover new functionalities. A non-destructive low-energy hydrogen plasma implantation experiment has been performed in strongly co [展开] ...

#### 2020年, 第15卷 第1期　出版日期：2020-02-15

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 Select Tetrapartite entanglement features of W-Class state in uniform acceleration Qian Dong, Ariadna J. Torres-Arenas, Guo-Hua Sun, Shi-Hai Dong Frontiers of Physics. 2020, 15 (1): 11602-.   https://doi.org/10.1007/s11467-019-0940-1 摘要   PDF (1004KB) Using the single-mode approximation, we first calculate entanglement measures such as negativity (1–3 and 1–1 tangles) and von Neumann entropy for a tetrapartite W-Class system in noninertial frame and then analyze the whole entanglement measures, the residual π4 and geometric Π4 average of tangles. Notice that the difference between π4 and Π4 is very small or disappears with the increasing accelerated observers. The entanglement properties are compared among the different cases from one accelerated observer to four accelerated observers. The results show that there still exists entanglement for the complete system even when acceleration r tends to infinity. The degree of entanglement is disappeared for the 1–1 tangle case when the acceleration r>0.472473. We reexamine the Unruh effect in noninertial frames. It is shown that the entanglement system in which only one qubit is accelerated is more robust than those entangled systems in which two or three or four qubits are accelerated. It is also found that the von Neumann entropy S of the total system always increases with the increasing accelerated observers, but the Sκξ and Sκζδ with two and three involved noninertial qubits first increases and then decreases with the acceleration parameter r, but they are equal to constants 1 and 0.811278 respectively for zero involved noninertial qubit.
 Select Electromagnetically induced transparency in novel dual-band metamaterial excited by toroidal dipolar response Zhao-Yang Shen, He-Lin Yang, Xuan Liu, Xiao-Jun Huang, Tian-Yu Xiang, Jiong Wu, Wei Chen Frontiers of Physics. 2020, 15 (1): 12601-.   https://doi.org/10.1007/s11467-019-0928-x 摘要   PDF (3371KB) We demonstrated a novel metamaterial with dual-band electromagnetically induced transparency (EIT) via simulation, experiment and numerical analysis, with resonance frequencies of the transparency peaks of 7.60 and 10.27 GHz. The E–ε metamaterial unit cells were composed of E-shaped and ε-shaped patterns. By analyzing the surface current distribution and the magnetic field, we qualitatively verified the toroidal dipole response in the E–ε metamaterial at 10.27 GHz. Meanwhile, by calculating the multipole’s radiated power, we found that the two transparency peaks were due to the excitation of the electric and toroidal dipole responses. By changing the incident angle from 0° to 60°, we observed changes in transmission spectra, and the quality factors (Q-factors) of the two transparency peaks increased. In addition, the proposed E–ε metamaterial can be designed to act as a refractive index sensor or other electronic equipment for the control of electromagnetic waves.
 Select Self-trapped spatially localized states in combined linear-nonlinear periodic potentials Jin-Cheng Shi, Jian-Hua Zeng Frontiers of Physics. 2020, 15 (1): 12602-.   https://doi.org/10.1007/s11467-019-0930-3 摘要   PDF (2105KB) We analyze the existence and stability of two kinds of self-trapped spatially localized gap modes, gap solitons and truncated nonlinear Bloch waves, in one- and two-dimensional optical or matter-wave media with self-focusing nonlinearity, supported by a combination of linear and nonlinear periodic lattice potentials. The former is found to be stable once placed inside a single well of the nonlinear lattice, it is unstable otherwise. Contrary to the case with constant self-focusing nonlinearity, where the latter solution is always unstable, here, we demonstrate that it nevertheless can be stabilized by the nonlinear lattice since the model under consideration combines the unique properties of both the linear and nonlinear lattices. The practical possibilities for experimental realization of the predicted solutions are also discussed.
 Select Visualizing quantum phenomena at complex oxide interfaces: An atomic view from scanning transmission electron microscopy Hangwen Guo, Mohammad Saghayezhian, Zhen Wang, Yimei Zhu, Jiandi Zhang, Ward Plummer Frontiers of Physics. 2020, 15 (1): 13401-.   https://doi.org/10.1007/s11467-019-0942-z 摘要   PDF (4176KB) Complex oxide interfaces have been one of the central focuses in condensed matter physics and material science. Over the past decade, aberration corrected scanning transmission electron microscopy and spectroscopy has proven to be invaluable to visualize and understand the emerging quantum phenomena at an interface. In this paper, we briefly review some recent progress in the utilization of electron microscopy to probe interfaces. Specifically, we discuss several important challenges for electron microscopy to advance our understanding on interface phenomena, from the perspective of variable temperature, magnetism, electron energy loss spectroscopy analysis, electronic symmetry, and defects probing.
 Select Modulation of the electronic states of perovskite SrCrO3 thin films through protonation via low-energy hydrogen plasma implantation approaches Meng Wu, Shanquan Chen, Chuanwei Huang, Xing Ye, Haiping Zhou, Xiaochun Huang, Kelvin H. L. Zhang, Wensheng Yan, Lihua Zhang, Kisslinger Kim, Yingge Du, Scott Chambers, Jin-Cheng Zheng, Hui-Qiong Wang Frontiers of Physics. 2020, 15 (1): 13601-.   https://doi.org/10.1007/s11467-019-0923-2 摘要   PDF (1900KB) Hydrogenation of transition metal oxides offers a powerful platform to tailor physical functionalities as well as for potential applications in modern electronic technologies. An ideal nondestructive and efficient hydrogen incorporation approach is important for the realistic technological applications. We demonstrate the proton injection on SrCrO3 thin films via an efficient low-energy hydrogen plasma implantation experiments, without destroying the original lattice framework. Hydrogen ions accumulate largely at the interfacial regions with amorphous character which extend about one-third of the total thickness. The HxSrCrO3 (HSCO) thin films appear like exfoliated layers which however retain the fully strained state with distorted perovskite structure. Proton doping induces the change of Cr oxidation state from Cr4+ to Cr3+ in HSCO thin films and a transition from metallic to insulating phase. Our investigations suggest an attractive platform in manipulating the electronic phases in proton-based approaches and may offer a potential peeling off strategy for nanoscale devices through low-energy hydrogen plasma implantation approaches.
 Select Motile parameters of cell migration in anisotropic environment derived by speed power spectrum fitting with double exponential decay Yan-Ping Liu (刘艳平), Xiang Li (李翔), Jing Qu (屈静), Xue-Juan Gao (高学娟), Qing-Zu He (何情祖), Li-Yu Liu (刘雳宇), Ru-Chuan Liu (刘如川), Jian-Wei Shuai (帅建伟) Frontiers of Physics. 2020, 15 (1): 13602-.   https://doi.org/10.1007/s11467-019-0929-9 摘要   PDF (4094KB) Cell migration through anisotropic microenvironment is critical to a wide variety of physiological and pathological processes. However, adequate analytical tools to derive motile parameters to characterize the anisotropic migration are lacking. Here, we proposed a method to obtain the four motile parameters of migration cells based on the anisotropic persistent random walk model which is described by two persistence times and two migration speeds at perpendicular directions. The key process is to calculate the velocity power spectra of cell migration along intrinsically perpendicular directions respectively, then to apply maximum likelihood estimation to derive the motile parameters from the power spectra fitting with double exponential decay. The simulation results show that the averaged persistence times and the corrected migration speeds can be good estimations for motile parameters of cell migration.
 Select Equivariant PT-symmetric real Chern insulators Y. X. Zhao Frontiers of Physics. 2020, 15 (1): 13603-.   https://doi.org/10.1007/s11467-019-0943-y 摘要   PDF (737KB) It was understood that Chern insulators cannot be realized in the presence of PT symmetry. In this paper, we reveal a new class of PT-symmetric Chern insulators, which has internal degrees of freedom forming real representations of a symmetry group with a complex endomorphism field. As a generalization to the conventional 2n-dimensional Chern insulators with integer n≥1, these PT-symmetric Chern insulators have the n-th complex Chern number as their topological invariant, and have a $Z$classification given by the equivariant orthogonal K theory. Thus, in a fairly different sense, there exist ubiquitously Chern insulators with PT symmetry. By generalizing the Thouless charge pump argument, we find that, for a PT-symmetric Chern insulator with Chern number $υ$, there are equally many $υ$ flavors of coexisting left- and right-handed chiral modes. Chiral modes with opposite chirality are complex conjugates to each other as complex representations of the internal symmetry group, but are not isomorphic. For the physical dimensionality d = 2, the PT-symmetric Chern insulators may be realized in artificial systems including photonic crystals and periodic mechanical systems.
 Select Nonlocalized clustering and evolution of cluster structure in nuclei Bo Zhou, Yasuro Funaki, Hisashi Horiuchi, Akihiro Tohsaki Frontiers of Physics. 2020, 15 (1): 14401-.   https://doi.org/10.1007/s11467-019-0917-0 摘要   PDF (10188KB) We explain various facets of the THSR (Tohsaki–Horiuchi–Schuck-Röpke) wave function. We first discuss the THSR wave function as a wave function of cluster-gas state, since the THSR wave function was originally introduced to elucidate the 3α-condensate-like character of the Hoyle state ($02+$ state) of 12C. We briefly review the cluster-model studies of the Hoyle state in 1970’s in order to explain how there emerged the idea to assign the α condensate character to the Hoyle state. We then explain that the THSR wave function can describe very well also non-gaslike ordinary cluster states with spatial localization of clusters. This fact means that the dynamical motion of clusters is of nonlocalized nature just as in gas-like states of clusters and the localization of clusters is due to the inter-cluster Pauli principle which is against the close approach of two clusters. The nonlocalized cluster dynamics is formulated by the container model of cluster dynamics. The container model describes gas-like state and non-gaslike states as the solutions of the Hill–Wheeler equation with respect to the size parameter of THSR wave function which is just the size parameter of the container. When we notice that fact that the THSR wave function with the smallest value of size parameter is equivalent to the shell-model wave function, we see that the container model describes the evolution of cluster structure from the ground state with shell-model structure up to the gas-like cluster state via ordinary non-gaslike cluster states. For the description of various cluster structure, more generation of THSR wave function have been introduced and we review some typical examples with their actual applications.
 Select Extraction of gravitational wave signals with optimized convolutional neural network Hua-Mei Luo, Wenbin Lin, Zu-Cheng Chen, Qing-Guo Huang Frontiers of Physics. 2020, 15 (1): 14601-.   https://doi.org/10.1007/s11467-019-0936-x 摘要   PDF (1257KB) Gabbard et al. have demonstrated that convolutional neural networks can achieve the sensitivity of matched filtering in the recognization of the gravitational-wave signals with high efficiency [Phys. Rev. Lett. 120, 141103 (2018)]. In this work we show that their model can be optimized for better accuracy. The convolutional neural networks typically have alternating convolutional layers and max pooling layers, followed by a small number of fully connected layers. We increase the stride in the max pooling layer by 1, followed by a dropout layer to alleviate overfitting in the original model. We find that these optimizations can effectively increase the area under the receiver operating characteristic curve for various tests on the same dataset.
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