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Volume 35 Issue 11
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Solutions to Nonlocal Integrable Discrete Nonlinear Schrödinger Equations via Reduction
Ya-Hong Hu, Jun-Chao Chen
Chin. Phys. Lett. 2018, 35 (11): 110201 .   DOI: 10.1088/0256-307X/35/11/110201
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Solutions to local and nonlocal integrable discrete nonlinear Schrödinger (IDNLS) equations are studied via reduction on the bilinear form. It is shown that these solutions to IDNLS equations can be expressed in terms of the single Casorati determinant under different constraint conditions.
Properties of One-Dimensional Highly Polarized Fermi Gases
Ya-Dong Song, Xiao-Ming Cai
Chin. Phys. Lett. 2018, 35 (11): 110301 .   DOI: 10.1088/0256-307X/35/11/110301
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Using both the exact Bethe ansatz method and the variational method, we study properties of the one-dimensional Fermi polaron. We focus on the binding energy, effective mass, momentum distributions, Tan contact and correlation functions. As the attraction increases, the impurity is more tightly bound and correlated with the surrounding particles, and the size of formed polaron decreases. In addition, compared with the Bethe ansatz method, the variational method is totally qualified to study the one-dimensional Fermi polaron. The intrinsic reason is that the number of particle-hole excitations in a Fermi sea, caused by a single impurity, is always rather small. The variational method can be well extended to other impurity systems.
Exact Entanglement Dynamics in Three Interacting Qubits
Wen-Bin He, Xi-Wen Guan
Chin. Phys. Lett. 2018, 35 (11): 110302 .   DOI: 10.1088/0256-307X/35/11/110302
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Motivated by recent experimental studies on coherent dynamics transfer in three interacting atoms or electron spins [Phys. Rev. Lett 114 (2015) 113002, Phys. Rev. Lett 120 (2018) 243604], here we study entanglement entropy transfer in three interacting qubits. We analytically calculate time evolutions of wave function, density matrix and entanglement of the system. We find that initially entangled two qubits may alternatively transfer their entanglement entropy to other two qubit pairs. Thus dynamical evolution of three interacting qubits may produce a genuine three-partite entangled state through entanglement entropy transfers. In particular, different pairwise interactions of the three qubits endow symmetric and asymmetric evolutions of the entanglement transfer, characterized by the quantum mutual information and concurrence. Finally, we discuss an experimental proposal of three Rydberg atoms for testing the entanglement dynamics transfer of this kind.
Exact Equivalence between Quantum Adiabatic Algorithm and Quantum Circuit Algorithm
Hongye Yu, Yuliang Huang, Biao Wu
Chin. Phys. Lett. 2018, 35 (11): 110303 .   DOI: 10.1088/0256-307X/35/11/110303
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We present a rigorous proof that quantum circuit algorithm can be transformed into quantum adiabatic algorithm with the exact same time complexity. This means that from a quantum circuit algorithm of $L$ gates we can construct a quantum adiabatic algorithm with time complexity of $O(L)$. Additionally, our construction shows that one may exponentially speed up some quantum adiabatic algorithms by properly choosing an evolution path.
Simulation of Intermediate State Absorption Enhancement in Rare-Earth Ions by Polarization Modulated Femtosecond Laser Field
Wen-Jing Cheng, Shi-Hua Zhao
Chin. Phys. Lett. 2018, 35 (11): 113201 .   DOI: 10.1088/0256-307X/35/11/113201
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We extend the third perturbation theory to study the polarization control behavior of the intermediate state absorption in Nd$^{3+}$ ions. The results show that coherent interference can occur between the single-photon and three-photon excitation pathways, and depends on the central frequency of the femtosecond laser field. Moreover, single-photon and three-photon absorptions have different polarization control efficiencies, and the relative weight of three-photon absorption in the whole excitation processes can increase with increasing the laser intensity. Therefore, the enhancement or suppression of the intermediate state absorption can be realized and manipulated by properly designing the intensity and central frequency of the polarization modulated femtosecond laser field. This research can not only enrich theoretical research methods for the up-conversion luminescence manipulation of rare-earth ions, but also can provide a clear physical picture for understanding and controlling multi-photon absorption in a multiple energy level system.
Optical Tunability of Silver-Dielectric-Silver Multi-Layered Cylindrical Nanotubes Using Quasi-Static Approximation
Zhao-Wang Wu, Ye-Wan Ma, Li-Hua Zhang, Xun-Chang Yin, Sheng-Bao Zhan
Chin. Phys. Lett. 2018, 35 (11): 114201 .   DOI: 10.1088/0256-307X/35/11/114201
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Local surface plasmon resonances (LSPRs) of silver-dielectric-silver multi-layered (SDS-ML) nanotubes are studied by theoretical calculations. Based on quasi-static approximation, the absorption cross section of SDS-ML nanotubes is plotted as a function of wavelength. The results show that SDS-ML nanotubes exhibit strong coupling between the cylindrical silver and nanotubes. The absorption spectra of LSPRs are strongly influenced by changing the radius of the inner core and outer nanotube shell. The longer wavelength is red-shifted by increasing the radius of the inner core and outer shell, while the short wavelength shows the opposite properties. These phenomena are explained by the plasmon hybridization theory. In addition, for clarity, the distributions of electric field intensity at their plasmon resonance wavelengths are also studied.
Using Reduced Graphene Oxide to Generate Q-Switched Pulses in Er-Doped Fiber Laser
Lu Li, Rui-Dong Lv, Si-Cong Liu, Zhen-Dong Chen, Jiang Wang, Yong-Gang Wang, Wei Ren
Chin. Phys. Lett. 2018, 35 (11): 114202 .   DOI: 10.1088/0256-307X/35/11/114202
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Using the reduced graphene oxide (rGO) as a saturable absorber (SA) in an Er-doped fiber (EDF) laser cavity, we obtain the Q-switching operation. The rGO SA is prepared by depositing the GO on fluorine mica (FM) using the thermal reduction method. The modulation depth of rGO/FM is measured to be 3.2%. By incorporating the rGO/FM film into the EDF laser cavity, we obtain stable Q-switched pulses. The shortest pulse duration is 3.53 μs, and the maximum single pulse energy is 48.19 nJ. The long-term stability of working is well exhibited. The experimental results show that the rGO possesses potential photonics applications.
Synchronously Pumped Mode-Locked 1.89μm Tm-Doped Fiber Laser with High Detuning Toleration
Gen Li, Yong Zhou, Shu-Jie Li, PeiJun Yao, Wei-qing Gao, Chun Gu, Li-Xin Xu
Chin. Phys. Lett. 2018, 35 (11): 114203 .   DOI: 10.1088/0256-307X/35/11/114203
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We propose and demonstrate a synchronously pumped mode-locked Tm-doped fiber (TDF) laser without any extra mode-locking elements. Pumped by a 1.56 μm pulse fiber laser, the TDF laser generates 1.17 ps pulses with a spectral width of 9.7 nm and a repetition rate of 9.33 MHz. The emission wavelength is tunable along with the cavity length detuning in a wide range of 3 mm. The high detuning toleration is beneficial to achieve high temperature and vibration stability in all-fiber configuration lasers.
Near-Range Large Field-of-View Three-Dimensional Photon-Counting Imaging with a Single-Pixel Si-Avalanche Photodiode
Guang-Yue Shen, Tian-Xiang Zheng, Bing-Cheng Du, Yang Lv, E Wu, Zhao-Hui Li, Guang Wu
Chin. Phys. Lett. 2018, 35 (11): 114204 .   DOI: 10.1088/0256-307X/35/11/114204
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Large field-of-view (FoV) three-dimensional (3D) photon-counting imaging is demonstrated with a single-pixel single-photon detector based on a Geiger-mode Si-avalanche photodiode. By removing the collecting lens (CL) before the detector, the FoV is expanded to $\pm $10$^{\circ}$. Thanks to the high detection efficiency, the signal-to-noise ratio of the imaging system is as high as 7.8 dB even without the CL when the average output laser pulse energy is about 0.45 pJ/pulse for imaging the targets at a distance of 5 m. A 3D image overlaid with the reflectivity data is obtained according to the photon-counting time-of-flight measurement and the return photon intensity.
A Sound Field Separation and Reconstruction Technique Based on Reciprocity Theorem and Fourier Transform
Xiao-Lei Li, Ning Wang, Da-Zhi Gao, Qi Li
Chin. Phys. Lett. 2018, 35 (11): 114301 .   DOI: 10.1088/0256-307X/35/11/114301
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We show a method to separate the sound field radiated by a signal source from the sound field radiated by noise sources and to reconstruct the sound field radiated by the signal source. The proposed method is based on reciprocity theorem and the Fourier transform. Both the sound field and its gradient on a measurement surface are needed in the method. Evanescent waves are considered in the method, which ensures a high resolution reconstruction in the near field region of the signal source when evanescent waves can be measured. A simulation is given to verify the method and the influence of measurement noise on the method is discussed.
Analysis of Second-Harmonic Generation of Low-Frequency Dilatational Lamb Waves in a Two-Layered Composite Plate
Han Chen, Ming-Xi Deng, Ning Hu, Ming-Liang Li, Guang-Jian Gao, Yan-Xun Xiang
Chin. Phys. Lett. 2018, 35 (11): 114302 .   DOI: 10.1088/0256-307X/35/11/114302
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We analyze the effect of second-harmonic generation (SHG) of primary Lamb wave propagation in a two-layered composite plate, and then investigate the influence of interfacial properties on the said effect at low frequency. It is found that changes in the interfacial properties essentially affect the dispersion relation and then the maximum cumulative distance of the double-frequency Lamb wave generated. This will remarkably influence the efficiency of SHG. To overcome the complications arising from the inherent dispersion and multimode natures in analyzing the SHG effect of Lamb waves, the present work focuses on the analysis of the SHG effect of low-frequency dilatational Lamb wave propagation. Both the numerical analysis and finite element simulation indicate that the SHG effect of low-frequency dilatational Lamb wave propagation is found to be much more sensitive to changes in the interfacial properties than primary Lamb waves. The potential of using the SHG effect of low-frequency dilatational Lamb waves to characterize a minor change in the interfacial properties is analyzed.
Interaction between Dislocation and Twinning Boundary under Incremental Loading in $\alpha$-Titanium
Xiang-Yue Liu, Hong Zhang, Xin-Lu Cheng
Chin. Phys. Lett. 2018, 35 (11): 116201 .   DOI: 10.1088/0256-307X/35/11/116201
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The lattice dislocation interacting with grain boundary in the polycrystal exerts an evident influence on the materials' strength and toughness. A comprehensive study regarding the dislocation–twinning boundary (TB) interaction in $\alpha$-titanium and TB migration is performed by employing molecular dynamic simulation. We analyze the interactions between dislocation and TB, under the conditions of plastic deformation and thermal stress, including the interaction between pure edge $\langle a\rangle$ dislocation and $({11\bar{2}2})$ TB and the interaction between mixed type $\langle a\rangle$ dislocations and $({10\bar{1}1})$ TB at 10 K/300 K. The $\langle {c+a} \rangle$ pyramidal transmitting slip mode is motivated in the case of edge dislocation–$({11\bar{2}2})$ interaction at 300 K and then transforms into basal-dissociated dislocation after experiencing the complex dissociation and combination. The basal-dissociated pyramidal partial dislocation located in the second grain can be driven to penetrate through the second grain leaving the multiple stacking faults behind. Dissociation of incident basal dislocation on $({10\bar{1}1})$ TB results in a nucleation of a $({10\bar{1}1})$ twin embryo in twin crystals at room temperature. We determine the nature of the generated defects by means of the Burgers circuit analysis.
Coherent Acoustic Phonon and Its Chirping in Dirac Semimetal Cd$_{3}$As$_{2}$
Fei Sun, M. Yang, M. W. Yang, Q. Wu, H. Zhao, X. Ye, Youguo Shi, Jimin Zhao
Chin. Phys. Lett. 2018, 35 (11): 116301 .   DOI: 10.1088/0256-307X/35/11/116301
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Ultrafast optical spectroscopy of a single crystal of a Dirac semimetal Cd$_{3}$As$_{2}$ is carried out. An acoustic phonon (AP) mode with central frequency $f=0.037$ THz (i.e., 1.23 cm$^{-1}$ or 0.153 meV) is unambiguously generated and detected, which we attribute to laser-induced thermal strain. An AP chirping (i.e., variation of the phonon frequency) is clearly detected, which is ascribed to heat capacity variation with time. By comparing our experimental results and the theoretical model, we obtain a chirping time constant, which is 31.2 ps at 6 K and 19.8 ps at 300 K, respectively. Significantly, we identify an asymmetry in the AP frequency domain peak and find that it is caused by the chirping, instead of a Fano resonance. Moreover, we experimentally demonstrate that the central frequency of AP is extremely stable with varying laser fluence, as well as temperature, which endows Cd$_{3}$As$_{2}$ application potentials in thermoelectric devices.
Nonlinear Dicke Quantum Phase Transition and Its Quantum Witness in a Cavity-Bose–Einstein-Condensate System
Wang-Jun Lu, Zhen Li, Le-Man Kuang
Chin. Phys. Lett. 2018, 35 (11): 116401 .   DOI: 10.1088/0256-307X/35/11/116401
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We investigate nonlinear Dicke quantum phase transition (QPT) induced by inter-atomic nonlinear interaction and its quantum witness in a cavity-Bose–Einstein-condensate (BEC) system. It is shown that inter-atomic nonlinear interaction in a cavity BEC system can induce first-order Dicke QPT. It is found that this nonlinear Dicke QPT can happen in an arbitrary coupling regime of the cavity and atoms. It is demonstrated that the quantum speed limit time can witness the Dicke QPT through its sudden change at the critical point of the QPT.
Magnetotransport Properties of a Nodal Line Semimetal TiSi
Moran Gao, Junbao He, Wenliang Zhu, Shuai Zhang, Xinmin Wang, Jing Li, Chaoyang Ma, Hui Liang, Zhian Ren, Genfu Chen
Chin. Phys. Lett. 2018, 35 (11): 117101 .   DOI: 10.1088/0256-307X/35/11/117101
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We report the magnetoresistance (MR), de Haas-van Alphen (dHvA) effect and Hall effect measurements on a single crystal of TiSi, which is predicted to be a nodal line semimetal. With application of a magnetic field, a metal-to-insulator-like transition in $\rho(T)$ and a nonsaturating MR are observed at low temperatures. The dHvA oscillations reveal a small Fermi-surface pocket with a nontrivial Berry phase. The analysis of the nonlinear Hall resistivity shows that TiSi is a multiband system with low carrier densities and high mobilities. All these results unambiguously prove the existence of Dirac fermions in TiSi.
Ge Complementary Tunneling Field-Effect Transistors Featuring Dopant Segregated NiGe Source/Drain
Junkang Li, Yiming Qu, Siyu Zeng, Ran Cheng, Rui Zhang, Yi Zhao
Chin. Phys. Lett. 2018, 35 (11): 117201 .   DOI: 10.1088/0256-307X/35/11/117201
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Ge complementary tunneling field-effect transistors (TFETs) are fabricated with the NiGe metal source/drain (S/D) structure. The dopant segregation method is employed to form the NiGe/Ge tunneling junctions of sufficiently high Schottky barrier heights. As a result, the Ge p- and n-TFETs exhibit decent electrical properties of large ON-state current and steep sub-threshold slope ($S$ factor). Especially, $I_{\rm d}$ of 0.2 $\mu$A/μm is revealed at $V_{\rm g}-V_{\rm th}=V_{\rm d}=\pm 0.5$ V for Ge pTFETs, with the $S$ factor of 28 mV/dec at 7 K.
Rare-Earth Chalcogenides: A Large Family of Triangular Lattice Spin Liquid Candidates
Weiwei Liu, Zheng Zhang, Jianting Ji, Yixuan Liu, Jianshu Li, Xiaoqun Wang, Hechang Lei, Gang Chen, Qingming Zhang
Chin. Phys. Lett. 2018, 35 (11): 117501 .   DOI: 10.1088/0256-307X/35/11/117501
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Frustrated quantum magnets are expected to host many exotic quantum spin states like quantum spin liquid (QSL), and have attracted numerous interest in modern condensed matter physics. The discovery of the triangular lattice spin liquid candidate YbMgGaO$_4$ stimulated an increasing attention on the rare-earth-based frustrated magnets with strong spin-orbit coupling. Here we report the synthesis and characterization of a large family of rare-earth chalcogenides AReCh$_2$ (A = alkali or monovalent ions, Re = rare earth, Ch = O, S, Se). The family compounds share the same structure ($R\bar{3}m$) as YbMgGaO$_4$, and antiferromagnetically coupled rare-earth ions form perfect triangular layers that are well separated along the $c$-axis. Specific heat and magnetic susceptibility measurements on NaYbO$_2$, NaYbS$_2$ and NaYbSe$_2$ single crystals and polycrystals, reveal no structural or magnetic transition down to 50 mK. The family, having the simplest structure and chemical formula among the known QSL candidates, removes the issue on possible exchange disorders in YbMgGaO$_4$. More excitingly, the rich diversity of the family members allows tunable charge gaps, variable exchange coupling, and many other advantages. This makes the family an ideal platform for fundamental research of QSLs and its promising applications.
First Principle Study on Optical Properties of Tri-Group Doped (6,6) SiC Nanotubes
Pei GONG, Ya-Lin LI, Ya-Hui JIA, Xiao-Yong FANG
Chin. Phys. Lett. 2018, 35 (11): 117801 .   DOI: 10.1088/0256-307X/35/11/117801
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The optical properties of tri-group (B, Al, Ga, In) doped (6,6) SiC nanotubes (SiCNTs) are studied from first principles. The results show that the main absorption and dispersion of SiCNTs caused by the intrinsic transition appear in the ultraviolet-visible region (below 500 nm), and the tri-group doping increases the minimum dielectric constant value resulting in enhanced transmittance. In addition, the tri-group doping can introduce a weak absorption and dispersion region in the near-mid-infrared region, and the response peak blue shifts as the diameter of the doping atom increases. Comparative studies of reflectance, absorptivity, and transmittance show that the key factors affecting the transmittance of SiCNTs are reflectance (or refractive index) rather than absorption coefficient.
Thermal Characteristics of PVA-PANI-ZnS Nanocomposite Film Synthesized by Gamma Irradiation Method
Afarin Bahrami, Kasra Behzad, Nastaran Faraji, Alireza Kharazmi
Chin. Phys. Lett. 2018, 35 (11): 117802 .   DOI: 10.1088/0256-307X/35/11/117802
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Gamma irradiation is employed for in situ preparation of PVA-PANI-ZnS nanocomposite. The irradiation dose is varied from 10 to 40 kGy at 10 kGy intervals. The XRD result confirms the formation of crystalline phases corresponding to ZnS nanoparticles, PVA and PANI. Field emission scanning electron microscopy shows the formation of agglomerated PANI along the PVA backbone, within which the ZnS nanoparticles are dispersed. UV-visible spectroscopy is conducted to measure the transmittance spectra of samples revealing the electronic absorption characteristics of ZnS and PANI nanoparticles. Photo-acoustic (PA) setup is installed to investigate the thermal properties of samples. The PA spectroscopy indicates a high value of thermal diffusivity for samples due to the presence of ZnS and PANI nanoparticles. Moreover, at higher doses, the more polymerization and formation of PANI and ZnS nanoparticles result in enhancement of thermal diffusivity.
Total Ionization Dose Effects on Charge Storage Capability of Al$_{2}$O$_{3}$/HfO$_{2}$/Al$_{2}$O$_{3}$-Based Charge Trapping Memory Cell
Yan-Nan Xu, Jin-Shun Bi, Gao-Bo Xu, Bo Li, Kai Xi, Ming Liu, Hai-Bin Wang, Li Luo
Chin. Phys. Lett. 2018, 35 (11): 118501 .   DOI: 10.1088/0256-307X/35/11/118501
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Because of the discrete charge storage mechanism, charge trapping memory (CTM) technique is a good candidate for aerospace and military missions. The total ionization dose (TID) effects on CTM cells with Al$_{2}$O$_{3}$/HfO$_{2}$/Al$_{2}$O$_{3}$ (AHA) high-$k$ gate stack structure under in-situ 10 keV x-rays are studied. The $C$–$V$ characteristics at different radiation doses demonstrate that charge stored in the device continues to be leaked away during the irradiation, thereby inducing the shift of flatband voltage ($V_{\rm fb}$). The dc memory window shows insignificant changes, suggesting the existence of good P/E ability. Furthermore, the physical mechanisms of TID induced radiation damages in AHA-based CTM are analyzed.
Effect of Torsion on Cisplatin-Induced DNA Condensation
Bo Li, Chao Ji, Xi-Ming Lu, Yu-Ru Liu, Wei Li, Shuo-Xing Dou, Hui Li, Peng-Ye Wang
Chin. Phys. Lett. 2018, 35 (11): 118701 .   DOI: 10.1088/0256-307X/35/11/118701
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We investigate the effect of torsion on DNA condensation with the covalently closed circular DNA as the torsion-constrained system, using an atomic force microscope. It is found that there are two stages in the DNA condensation process under torsional constraint. At the early stage, the low torsion will accelerate DNA condensation by promoting the formation of micro-loops or intersection structures; while at the later stage, the increasing torsion will slow it down by preventing the crosslinking of cisplatin and DNA since the DNA molecule becomes more rigid. Our results show the important role of torsion in DNA condensation and sheds new light on the mechanism for DNA condensation.
Effect of Kinetic Alfvén Waves on Electron Transport in an Ion-Scale Flux Rope
Bin-Bin Tang, Wen-Ya Li, Chi Wang, Lei Dai, Jin-Peng Han
Chin. Phys. Lett. 2018, 35 (11): 119401 .   DOI: 10.1088/0256-307X/35/11/119401
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At the Earth's magnetopause, the electron transport due to kinetic Alfvén waves (KAWs) is investigated in an ion-scale flux rope by the Magnetospheric Multiscale mission. Clear electron dropout around 90$^{\circ}$ pitch angle is observed throughout the flux rope, where intense KAWs are identified. The KAWs can effectively trap electrons by the wave parallel electric field and the magnetic mirror force, allowing electrons to undergo Landau resonance and be transported into more field-aligned directions. The pitch angle range for the trapped electrons is estimated from the wave analysis, which is in good agreement with direct pitch angle measurements of the electron distributions. The newly formed beam-like electron distribution is unstable and excites whistler waves, as revealed in the observations. We suggest that KAWs could be responsible for the plasma depletion inside a flux rope by this transport process, and thus be responsible for the formation of a typical flux rope.
22 articles