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Soliton Molecules, Asymmetric Solitons and Hybrid Solutions for (2+1)-Dimensional Fifth-Order KdV Equation
Zhao Zhang, Shu-Xin Yang, Biao Li
Chin. Phys. Lett. 2019, 36 (12):
120501
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DOI: 10.1088/0256-307X/36/12/120501
Soliton molecules were first discovered in optical systems and are currently a hot topic of research. We obtain soliton molecules of the (2+1)-dimensional fifth-order KdV system under a new resonance condition called velocity resonance in theory. On the basis of soliton molecules, asymmetric solitons can be obtained by selecting appropriate parameters. Based on the $N$-soliton solution, we obtain hybrid solutions consisting of soliton molecules, lump waves and breather waves by partial velocity resonance and partial long wave limits. Soliton molecules, and some types of special soliton resonance solutions, are stable under the meaning that the interactions among soliton molecules are elastic. Both soliton molecules and asymmetric solitons obtained may be observed in fluid systems because the fifth-order KdV equation describes the ion-acoustic waves in plasmas, shallow water waves in channels and oceans.
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Stress, Roughness and Reflectivity Properties of Sputter-Deposited B$_{4}$C Coatings for X-Ray Mirrors
Jia-Li Wu, Run-Ze Qi, Qiu-Shi Huang, Yu-Fei Feng, Zhan-Shan Wang, Zi-Hua Xin
Chin. Phys. Lett. 2019, 36 (12):
120701
.
DOI: 10.1088/0256-307X/36/12/120701
Boron carbide (B$_{4}$C) coatings have high reflectivity and are widely used as mirrors for free-electron lasers in the x-ray range. However, B$_{4}$C coatings fabricated by direct-current magnetron sputtering show a strong compressive stress of about $-3$ GPa. By changing the argon gas pressure and nitrogen-argon gas mixing ratio, we are able to reduce the intrinsic stress to less than $-1$ GPa for a 50-nm-thick B$_{4}$C coating. It is found that the stress in a coating deposited at 10 mTorr is $-0.69$ GPa, the rms roughness of the coating surface is 0.53 nm, and the coating reflectivity is 88%, which is lower than those of coatings produced at lower working pressures. When the working gas contains 8% nitrogen and 92% argon, the B$_{4}$C coating shows not only $-1.19$ GPa stress but also a low rms roughness of 0.16 nm, and the measured reflectivity is 93% at the wavelength of 0.154 nm.
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Photoexcited Blueshift and Redshift Switchable Metamaterial Absorber at Terahertz Frequencies
Zong-Cheng Xu, Liang Wu, Ya-Ting Zhang, De-Gang Xu, Jian-Quan Yao
Chin. Phys. Lett. 2019, 36 (12):
124202
.
DOI: 10.1088/0256-307X/36/12/124202
We propose a design and numerical study of an optically blueshift and redshift switchable metamaterial (MM) absorber in the terahertz regime. The MM absorber comprises a periodic array of metallic split-ring resonators (SRRs) with semiconductor silicon embedded in the gaps of MM resonators. The absorptive frequencies of the MM can be shifted by applying an external pump power. The simulation results show that, for photoconductivity of silicon ranging between 1 S/m and 4000 S/m, the resonance peak of the absorption spectra shifts to higher frequencies, from 0.67 THz to 1.63 THz, with a resonance tuning range of 59%. As the conductivity of silicon increases, the resonance frequencies of the MM absorber are continuously tuned from 1.60 THz to 1.16 THz, a redshift tuning range of 28%. As the conductivity increases above 30000 S/m, the resonance frequencies tend to be stable while the absorption peak has a merely tiny variation. The optical-tuned absorber has potential applications as a terahertz modulator or switch.
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Landau–Zener–Stückelberg Interference in Nonlinear Regime
Tong Wu, Yuxuan Zhou, Yuan Xu, Song Liu, Jian Li
Chin. Phys. Lett. 2019, 36 (12):
124204
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DOI: 10.1088/0256-307X/36/12/124204
Landau–Zener–Stückelberg (LZS) interference has drawn renewed attention to quantum information processing research because it is not only an effective tool for characterizing two-level quantum systems but also a powerful approach to manipulate quantum states. Superconducting quantum circuits, due to their versatile tunability and degrees of control, are ideal platforms for studying LZS interference phenomena. We use a superconducting Xmon qubit to study LZS interference by parametrically modulating the qubit transition frequency nonlinearly. For dc flux biasing of the qubit slightly far away from the optimal flux point, the qubit excited state population shows an interference pattern that is very similar to the standard LZS interference in linear regime, except that all bands shift towards lower frequencies when increasing the rf modulation amplitude. For dc flux biasing close to the optimal flux point, the negative sidebands and the positive sidebands behave differently, resulting in an asymmetric interference pattern. The experimental results are also in good agreement with our analytical and numerical simulations.
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Generation of Femtosecond Laser Pulse at 1.43GHz from an Optical Parametric Oscillator Based on LBO Crystal
Jia-Jun Song, Xiang-Hao Meng, Zhao-Hua Wang, Xian-Zhi Wang, Wen-Long Tian, Jiang-Feng Zhu, Shao-Bo Fang, Hao Teng, Zhi-Yi Wei
Chin. Phys. Lett. 2019, 36 (12):
124206
.
DOI: 10.1088/0256-307X/36/12/124206
A femtosecond LBO optical parametric oscillator (OPO) with widely adjustable repetition rate by fractionally decrement of the cavity length is demonstrated. The repetition rate of 755 MHz to 1.43 GHz at an interval of 75.5 MHz is realized, which is 10 to 19 times that of the pump laser. The properties of output signal at 750 nm at different repetition rates are studied. The power of signal decreases with increasing the repetition rate. The maximum power of 194 mW at the repetition rate of 755 MHz and the minimum power of 22 mW at repetition rate of 1.43 GHz for the signal at 750 nm are obtained for the pump power of 3 W.
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Identifying the Symmetry of an Object Based on Orbital Angular Momentum through a Few-Mode Fiber
Zhou-Xiang Wang, Yu-Chen Xie, Han Zhou, Shuang-Yin Huang, Min Wang, Rui Liu, Wen-Rong Qi, Qian-Qian Tian, Ling-Jun Kong, Chenghou Tu, Yongnan Li, Hui-Tian Wang
Chin. Phys. Lett. 2019, 36 (12):
124207
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DOI: 10.1088/0256-307X/36/12/124207
In recent years, orbital angular momentum (OAM), as a new usable degree of freedom of photons, has been widely applied in both classical optics and quantum optics. For example, digital spiral imaging uses the OAM spectrum of the output beam from the object to restore the symmetry information of the object. However, the related experiments have been carried out in free space so far. Due to the poor anti-noise performance, limited transmission distance and other reasons, the practicability is seriously restricted. Here, we have carried out a digital spiral imaging experiment through a few-mode fiber, to achieve the identification of the symmetry of object by measuring the OAM spectrum of the output beam. In experiment, we have demonstrated the identification of the symmetry of amplitude-only and phase-only objects with the two-, three- and four-fold rotational symmetries. We also give the understanding of the physics. We believe that our work has greatly improved the practical application of digital spiral imaging in remote sensing.
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Emergent Quantum Dynamics of Vortex-Line under Linear Local Induction Approximation
Gui-Hao Jia, Yu Xu, Xiao Kong, Cui-Xian Guo, Si-Lei Liu, Su-Peng Kou
Chin. Phys. Lett. 2019, 36 (12):
124701
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DOI: 10.1088/0256-307X/36/12/124701
Using the linear local induction approximation, we investigate the self-induced motion of a vortex-line that corresponds to the motion of a particle in quantum mechanics. Provided Kelvin waves, the effective Schrödinger equation, physical quantity operators, and the corresponding path-integral formula can be obtained. In particular, the effective Planck constant defined by parameters of vortex-line motion shows the mathematical relation between the two fields. The vortexline–particle mapping may help in understanding particle motion in quantum mechanics.
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Hole Injection Enhancement of MoO$_{3}$/NPB/Al Composite Anode
Yanjing Tang, Xianxi Yu, Shaobo Liu, Anran Yu, Jiajun Qin, Ruichen Yi, Yuan Pei, Chunqin Zhu, Xiaoyuan Hou
Chin. Phys. Lett. 2019, 36 (12):
127201
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DOI: 10.1088/0256-307X/36/12/127201
An ultra-thin molybdenum(VI) oxide (MoO$_{3})$ modification layer can significantly improve hole injection from an electrode even though the MoO$_{3}$ layer does not contact the electrode. We find that as the thickness of the organic layer between MoO$_{3}$ and the electrode increases, the hole injection first increases and it then decreases. The optimum thickness of 5 nm corresponds to the best current improvement 70%, higher than that in the device where MoO$_{3}$ directly contacts the Al electrode. According to the 4,4-bis[N-(1-naphthyl)-N-phenyl-amino] biphenyl (NPB)/MoO$_{3}$ interface charge transfer mechanism and the present experimental results, we propose a mechanism that mobile carriers generated at the interface and accumulated inside the device change the distribution of electric field inside the device, resulting in an increase of the probability of hole tunneling through the injection barrier from the electrode, which also explains the phenomenon of hole injection enhanced by MoO$_{3}$/NPB/Al composite anode. Based on this mechanism, different organic materials other than NPB were applied to form the composite electrode with MoO$_{3}$. Similar current enhancement effects are also observed.
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High Resolution Microwave B-Field Imaging Using a Micrometer-Sized Diamond Sensor
Wen-Hao He, Ming-Ming Dong, Zhen-Zhong Hu, Qi-Han Zhang, Bo Yang, Ying Liu, Xiao-Long Fan, Guan-Xiang Du
Chin. Phys. Lett. 2019, 36 (12):
127601
.
DOI: 10.1088/0256-307X/36/12/127601
We propose a diamond-based micron-scale sensor and perform high-resolution $B$-field imaging of the near-field distribution of coplanar waveguides. The sensor consists of diamond crystals attached to the tip of a tapered fiber with a physical size on the order of submicron. The amplitude of the $B$-field component $B$ is obtained by measuring the Rabi oscillation frequency. The result of Rabi sequence is fitted with a decayed sinusoidal. We apply the modulation-locking technique that demonstrates the vector-resolved field mapping of the micromachine coplanar waveguide structure (CPW). $B$-field line scan was performed on the CPW with a scan step size of 1.25 μm. To demonstrate vector resolved rf field sensing, a full field line scan acts (was performed) along four NV axes at a height of 50 μm above the device surface. The simulations are compared with the experimental results by vector-resolved measurement. This technique allows the measurement of weak microwave signals with a minimum resolvable modulation depth of 20 ppm. The sensor will have great interest in micron-scale resolved microwave $B$-field measurements, such as electromagnetic compatibility testing of microwave integrated circuits and characterization of integrated microwave components.
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18 articles
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