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Time-Modulated Hamiltonian for Interpreting Delayed-Choice Experiments via Mach–Zehnder Interferometers
Zhi-Yuan Li
Chin. Phys. Lett. 2016, 33 (08):
080302
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DOI: 10.1088/0256-307X/33/8/080302
Many delayed-choice experiments based on Mach–Zehnder interferometers (MZI) have been considered and made to address the fundamental problem of wave-particle duality. Conventional wisdom long holds that by inserting or removing the second beam splitter (BS2) in a controllable way, microscopic particles (photons, electrons, etc.) transporting within the MZI can lie in the quantum superposition of the wave and particle state as $\psi =a_{\rm w} \psi _{\rm wave} +a_{\rm p} \psi _{\rm particle}$. Here we present an alternative interpretation to these delayed-choice experiments. We notice that as the BS2 is purely classical, the inserting and removing operation of the BS2 imposes a time-modulated Hamiltonian $H_{\bmod} (t)=a(t)H_{\rm in} +b(t)H_{\rm out}$, instead of a quantum superposition of $H_{\rm in}$ and $H_{\rm out}$ as $H=a_{\rm w} H_{\rm in} +a_{\rm p} H_{\rm out}$, to act upon the incident wave function. Solution of this quantum scattering problem, rather than the long held quantum eigen-problem yields a synchronically time-modulated output wave function as $\psi _{\bmod} (t)=a(t)\psi _{\rm wave} +b(t)\psi _{\rm particle}$, instead of the stationary quantum superposition state $\psi =a_{\rm w} \psi _{\rm wave} +a_{\rm p} \psi _{\rm particle}$. As a result, the probability of particle output from the MZI behaves as if they are in the superposition of the wave and particle state when many events over time accumulation are counted and averaged. We expect that these elementary but insightful analyses will shed a new light on exploring basic physics beyond the long-held wisdom of wave-particle duality and the principle of complementarity.
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A Maxwell Demon Model Connecting Information and Thermodynamics
Pei-Yan Peng, Chang-Kui Duan
Chin. Phys. Lett. 2016, 33 (08):
080501
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DOI: 10.1088/0256-307X/33/8/080501
In the past decades several theoretical Maxwell's demon models have been proposed to exhibit effects such as refrigerating, doing work at the cost of information, and some experiments have been carried out to realize these effects. We propose a model with a two-level demon, information represented by a sequence of bits, and two heat reservoirs. The reservoir that the demon is interacting with depends on the bit. When the temperature difference between the two heat reservoirs is large enough, the information can be erased. On the other hand, when the information is pure enough, heat transfer from one reservoir to the other can happen, resulting in the effect of refrigeration. Genuine examples of such a system are discussed.
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Continuous Dynamic Rotation Measurements Using a Compact Cold Atom Gyroscope
Zhan-Wei Yao, Si-Bin Lu, Run-Bing Li, Kai Wang, Lei Cao, Jin Wang, Ming-Sheng Zhan
Chin. Phys. Lett. 2016, 33 (08):
083701
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DOI: 10.1088/0256-307X/33/8/083701
We present an experimental demonstration of the rotation measurement using a compact cold atom gyroscope. Atom interference fringes are observed in the stationary frame and the rotating frame, respectively. The phase shift and contrast of the interference fringe are experimentally investigated. The results show that the contrast of the interference fringe is well held when the platform is rotated, and the phase shift of the interference fringe is linearly proportional to the rotation rate of the platform. The long-term stability, which is evaluated by the overlapped Allan deviation, is $8.5\times10^{-6}$ rad/s over the integrating time of 1000 s.
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The Relationship of Cavitation to the Negative Acoustic Pressure Amplitude in Ultrasonic Therapy
Ting-Bo Fan, Juan Tu, Lin-Jiao Luo, Xia-Sheng Guo, Pin-Tong Huang, Dong Zhang
Chin. Phys. Lett. 2016, 33 (08):
084302
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DOI: 10.1088/0256-307X/33/8/084302
The relationship between the cavitation and acoustic peak negative pressure in the high-intensity focused ultrasound (HIFU) field is analyzed in water and tissue phantom. The peak negative pressure at the focus is determined by a hybrid approach combining the measurement with the simulation. The spheroidal beam equation is utilized to describe the nonlinear acoustic propagation. The waveform at the focus is measured by a fiber optic probe hydrophone in water. The relationship between the source pressure amplitude and the excitation voltage is determined by fitting the measured ratio of the second harmonic to the fundamental component at the focus, based on the model simulation. Then the focal negative pressure is calculated for arbitrary voltage excitation in water and tissue phantom. A portable B-mode ultrasound scanner is applied to monitor HIFU-induced cavitation in real time, and a passive cavitation detection (PCD) system is used to acquire the bubble scattering signals in the HIFU focal volume for the cavitation quantification. The results show that: (1) unstable cavitation starts to appear in degassed water when the peak negative pressure of HIFU signals reaches 13.5 MPa; and (2) the cavitation activity can be detected in tissue phantom by B-mode images and in the PCD system with HIFU peak negative pressures of 9.0 MPa and 7.8 MPa, respectively, which suggests that real-time B-mode images could be used to monitor the cavitation activity in two dimensions, while PCD systems are more sensitive to detect scattering and emission signals from cavitation bubbles.
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Monitoring the Heavy Element of Cr in Agricultural Soils Using a Mobile Laser-Induced Breakdown Spectroscopy System with Support Vector Machine
Yan-Hong Gu, Nan-Jing Zhao, Ming-Jun Ma, De-Shuo Meng, Yang Yu, Yao Jia, Li Fang, Jian-Guo Liu, Wen-Qing Liu
Chin. Phys. Lett. 2016, 33 (08):
085201
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DOI: 10.1088/0256-307X/33/8/085201
Due to its complicated matrix effects, rapid quantitative analysis of chromium in agricultural soils is difficult without the concentration gradient samples by laser-induced breakdown spectroscopy. To improve the analysis speed and accuracy, two calibration models are built with the support vector machine method: one considering the whole spectra and the other based on the segmental spectra input. Considering the results of the multiple linear regression analysis, three segmental spectra are chosen as the input variables of the support vector regression (SVR) model. Compared with the results of the SVR model with the whole spectra input, the relative standard error of prediction is reduced from 3.18% to 2.61% and the running time is saved due to the decrease in the number of input variables, showing the robustness in rapid soil analysis without the concentration gradient samples.
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Radiation Resistance of Fluorine-Implanted PNP Using Gated-Controlled Lateral PNP Transistor Structure
Xin Wang, Wu Lu, Wu-Ying Ma, Qi Guo, Zhi-Kuan Wang, Cheng-Fa He, Mo-Han Liu, Xiao-Long Li, Jin-Cheng Jia
Chin. Phys. Lett. 2016, 33 (08):
086101
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DOI: 10.1088/0256-307X/33/8/086101
The radiation damage responses of fluorinated and non-fluorinated lateral PNP transistors are studied with specially designed gated-controlled lateral PNP transistors that allow for the extraction of the oxide trapped charge ($N_{\rm ot}$) and interface trap ($N_{\rm it}$) densities. All the samples are exposed in the Co-60$\gamma $ ray with the dose rate of 0.5 Gy(Si)/s. After the irradiation, the buildup of $N_{\rm ot}$ and $N_{\rm it}$ of the samples with total dose is investigated by the gate sweep test technique. The results show that the radiation resistance of fluorinated lateral PNP transistors is significantly enhanced compared with the non-fluorinated ones.
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Analysis of the Intrinsic Uncertainties in the Laser-Driven Iron Hugoniot Experiment Based on the Measurement of Velocities
Huan Zhang, Xiao-Xi Duan, Chen Zhang, Hao Liu, Hui-Ge Zhang, Quan-Xi Xue, Qing Ye, Zhe-Bin Wang, Gang Jiang
Chin. Phys. Lett. 2016, 33 (08):
086202
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DOI: 10.1088/0256-307X/33/8/086202
One of the most challenging tasks in the laser-driven Hugoniot experiment is how to increase the reproducibility and precision of the experimental data to meet the stringent requirement in validating equation of state models. In such cases, the contribution of intrinsic uncertainty becomes important and cannot be ignored. A detailed analysis of the intrinsic uncertainty of the aluminum–iron impedance-match experiment based on the measurement of velocities is presented. The influence of mirror-reflection approximation on the shocked pressure of Fe and intrinsic uncertainties from the equation of state uncertainty of standard material are quantified. Furthermore, the comparison of intrinsic uncertainties of four different experimental approaches is presented. It is shown that, compared with other approaches including the most widely used approach which relies on the measurements of the shock velocities of Al and Fe, the approach which relies on the measurement of the particle velocity of Al and the shock velocity of Fe has the smallest intrinsic uncertainty, which would promote such work to significantly improve the diagnostics precision in such an approach.
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Porosity Evaluation and the Power Spectral Densities Analyses of Carbon–Nickel Composite Films Annealed at Different Temperatures
V. Dalouji, S. M. Elahi, A. Ghaderi, S. Solaymani
Chin. Phys. Lett. 2016, 33 (08):
086601
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DOI: 10.1088/0256-307X/33/8/086601
The densification and the fractal dimensions of carbon–nickel films annealed at different temperatures 300, 500, 800, and 1000$^{\circ}\!$C with emphasis on porosity evaluation are investigated. For this purpose, the refractive index of films is determined from transmittance spectra. Three different regimes are identified, $T < 500^{\circ}\!$C, 500$^{\circ}\!$C$\, < T < 800^{\circ}\!$C and $T>800^{\circ}\!$C. The Rutherford backscattering spectra show that with increasing the annealing temperature, the concentration of nickel atoms into films decreases. It is shown that the effect of annealing temperatures for increasing films densification at $T < 500^{\circ}\!$C and $T>800^{\circ}\!$C is greater than the effect of nickel concentrations. It is observed that the effect of decreasing nickel atoms into films at 500$^{\circ}\!$C$\, < T < 800^{\circ}\!$C strongly causes improving porosity and decreasing densification. The fractal dimensions of carbon–nickel films annealed from 300 to 500$^{\circ}\!$C are increased, while from 500 to 1000$^{\circ}\!$C these characteristics are decreased. It can be seen that at 800$^{\circ}\!$C, films have maximum values of porosity and roughness.
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Comparative Study of Monolayer and Bilayer Epitaxial Graphene Field-Effect Transistors on SiC Substrates
Ze-Zhao He, Ke-Wu Yang, Cui Yu, Qing-Bin Liu, Jing-Jing Wang, Xu-Bo Song, Ting-Ting Han, Zhi-Hong Feng, Shu-Jun Cai
Chin. Phys. Lett. 2016, 33 (08):
086801
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DOI: 10.1088/0256-307X/33/8/086801
Monolayer and bilayer graphenes have generated tremendous excitement as the potentially useful electronic materials due to their unique features. We report on monolayer and bilayer epitaxial graphene field-effect transistors (GFETs) fabricated on SiC substrates. Compared with monolayer GFETs, the bilayer GFETs exhibit a significant improvement in dc characteristics, including increasing current density $I_{\rm DS}$, improved transconductance $g_{\rm m}$, reduced sheet resistance $R_{\rm on}$, and current saturation. The improved electrical properties and tunable bandgap in the bilayer graphene lead to the excellent dc performance of the bilayer GFETs. Furthermore, the improved dc characteristics enhance a better rf performance for bilayer graphene devices, demonstrating that the quasi-free-standing bilayer graphene on SiC substrates has a great application potential for the future graphene-based electronics.
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Contribution of Surface Defects to the Interface Conductivity of SrTiO$_{3}$/LaAlO$_{3}$
Li Guan, Feng-Xue Tan, Guo-Qi Jia, Guang-Ming Shen, Bao-Ting Liu, Xu Li
Chin. Phys. Lett. 2016, 33 (08):
087301
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DOI: 10.1088/0256-307X/33/8/087301
Based on the first-principles method, the structural stability and the contribution of point defects such as O, Sr or Ti vacancies on two-dimensional electron gas of n- and p-type LaAlO$_{3}$/SrTiO$_{3}$ interfaces are investigated. The results show that O vacancies at p-type interfaces have much lower formation energies, and Sr or Ti vacancies at n-type interfaces are more stable than the ones at p-type interfaces under O-rich conditions. The calculated densities of states indicate that O vacancies act as donors and give a significant compensation to hole carriers, resulting in insulating behavior at p-type interfaces. In contrast, Sr or Ti vacancies tend to trap electrons and behave as acceptors. Sr vacancies are the most stable defects at high oxygen partial pressures, and the Sr vacancies rather than Ti vacancies are responsible for the insulator-metal transition of n-type interface. The calculated results can be helpful to understand the tuned electronic properties of LaAlO$_{3}$/SrTiO$_{3}$ heterointerfaces.
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Phase Transformation and Enhancing Electron Field Emission Properties in Microcrystalline Diamond Films Induced by Cu Ion Implantation and Rapid Annealing
Yan-Yan Shen, Yi-Xin Zhang, Ting Qi, Yu Qiao, Yu-Xin Jia, Hong-Jun Hei, Zhi-Yong He, Sheng-Wang Yu
Chin. Phys. Lett. 2016, 33 (08):
088101
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DOI: 10.1088/0256-307X/33/8/088101
Cu ion implantation and subsequent rapid annealing at 500$^{\circ}\!$C in N$_{2}$ result in low surface resistivity of 1.611 ohm/sq with high mobility of 290 cm$^{2}$V$^{-1}$S$^{-1}$ for microcrystalline diamond (MCD) films. Its electrical field emission behavior can be turned on at $E_{0}=2.6$ V/μm, attaining a current density of 19.5 $\mu$A/cm$^{2}$ at an applied field of 3.5 V/μm. Field emission scanning electron microscopy combined with Raman and x-ray photoelectron microscopy reveal that the formation of Cu nanoparticles in MCD films can catalytically convert the less conducting disorder/a-C phases into graphitic phases and can provoke the formation of nanographite in the films, forming conduction channels for electron transportation.
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Fabrication of GaN-Based Heterostructures with an InAlGaN/AlGaN Composite Barrier
Ru-Dai Quan, Jin-Cheng Zhang, Jun-Shuai Xue, Yi Zhao, Jing Ning, Zhi-Yu Lin, Ya-Chao Zhang, Ze-Yang Ren, Yue Hao
Chin. Phys. Lett. 2016, 33 (08):
088102
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DOI: 10.1088/0256-307X/33/8/088102
GaN-based heterostructures with an InAlGaN/AlGaN composite barrier on sapphire (0001) substrates are grown by a low-pressure metal organic chemical vapor deposition system. Compositions of the InAlGaN layer are determined by x-ray photoelectron spectroscopy, structure and crystal quality of the heterostructures are identified by high resolution x-ray diffraction, surface morphology of the samples are examined by an atomic force microscope, and Hall effect and capacitance–voltage measurements are performed at room temperature to evaluate the electrical properties of heterostructures. The Al/In ratio of the InAlGaN layer is 4.43, which indicates that the InAlGaN quaternary layer is nearly lattice-matched to the GaN channel. Capacitance–voltage results show that there is no parasitic channel formed between the InAlGaN layer and the AlGaN layer. Compared with the InAlGaN/GaN heterostructure, the electrical properties of the InAlGaN/AlGaN/GaN heterostructure are improved obviously. Influences of the thickness of the AlGaN layer on the electrical properties of the heterostructures are studied. With the optimal thickness of the AlGaN layer to be 5 nm, the 2DEG mobility, sheet density and the sheet resistance of the sample is 1889.61 cm$^{2}$/V$\cdot$s, $1.44\times10^{13}$ cm$^{-2}$ and as low as 201.1 $\Omega$/sq, respectively.
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High Efficiency and Stable Organic Light-Emitting Diodes Based on Thermally Activated Delayed Fluorescence Emitter
Xiao-Peng Lv, Hui Wang, Ling-Qiang Meng, Xiao-Fang Wei, Yong-Zhen Chen, Xiang-Bin Kong, Jian-Jun Liu, Jian-Xin Tang, Peng-Fei Wang, Ying Wang
Chin. Phys. Lett. 2016, 33 (08):
088501
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DOI: 10.1088/0256-307X/33/8/088501
High efficiency, stable organic light-emitting diodes (OLEDs) based on 2-pheyl-4'-carbazole-9-H-Thioxanthen-9-one-10,10-dioxide (TXO-PhCz) with different doping concentration are constructed. The stability of the encapsulated devices are investigated in detail. The devices with the 10 wt% doped TXO-PhCz emitter layer (EML) show the best performance with a current efficiency of 52.1 cd/A, a power efficiency of 32.7 lm/W, and an external quantum efficiency (EQE) of 17.7%. The devices based on the 10 wt%-doped TXO-PhCz EML show the best operational stability with a half-life time (LT50) of 80 h, which is 8 h longer than that of the reference devices based on fac-tris(2-phenylpyridinato)iridium(III) (Ir(ppy)$_{3}$). These indicate excellent stability of TXO-PhCz for redox and oxidation processes under electrical excitation and TXO-PhCz can be potentially used as the emitters for OLEDs with high efficiency and excellent stability. The high-performance device based on TXO-PhCz with high stability can be further improved by the optimization of the encapsulation technology and the development of a new host for TXO-PhCz.
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Superconducting Nanowire Single Photon Detector with Optical Cavity
Jie Liu, Li-Qun Zhang, Zhen-Nan Jiang, Kamal Ahmad, Jian-She Liu, Wei Chen
Chin. Phys. Lett. 2016, 33 (08):
088502
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DOI: 10.1088/0256-307X/33/8/088502
Increasing the detection efficiency (DE) is a hot issue in the development of the superconducting nanowire single photon detector (SNSPD). In this work, a cavity-integrated structure coupled to the SNSPD is used to enhance the light absorption of nanowire. Ultra-thin Nb films are successfully prepared by magnetron sputtering, which are used to fabricate Nb/Al SNSPD with the curve of 100 nm and the square area of $4\times4$ μm$^2$ by sputtering and the lift-off method. To characterize the optical and electrical performance of the cavity-integrated SNSPD, a reliable cryogenic research system is built up based on a He$^{3}$ system. To satisfy the need of light coupling, a packaging structure with collimator is conducted. Both DE and the dark count rates increase with $I_{\rm b}$. It is also found that the DE of SNSPD with cavities can be up to 0.17% at the temperature of 0.7 K under the infrared light of 1550 nm, which is obviously higher than that of the SNSPD directly fabricated upon silicon without any cavity structure.
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Efficiency of Blue Organic Light-emitting Diodes Enhanced by Employing an Exciton Feedback Layer
Qian-Qian Yu, Xu Zhang, Jing-Xuan Bi, Guan-Ting Liu, Qi-Wen Zhang, Xiao-Ming Wu, Yu-Lin Hua, Shou-Gen Yin
Chin. Phys. Lett. 2016, 33 (08):
088503
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DOI: 10.1088/0256-307X/33/8/088503
We report that a novel exciton feedback effect is observed by introducing the bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum (BAlq) inserted between the emitting layer (EML) and the electron transporting layer in blue organic light emitting diodes. As an exciton feedback layer (EFL), the BAlq does not act as a traditional hole blocking effect. The design of this kind of device structure can greatly reduce excitons' quenching due to accumulated space charge at the exciton formation interface. Meanwhile, the non-radiative energy transfer from EFL to the EML can also be utilized to enhance the excitons' formation, which is confirmed by the test of photolumimescent transient lifetime decay and electroluminescence enhancement of these devices. Accordingly, the optimal device presents the improved performances with the maximum current efficiency of 4.2 cd/A and the luminance of 24600 cd/m$^{2}$, which are about 1.45 times and 1.75 times higher than those of device A (control device) without the EFL, respectively. Simultaneously, the device shows an excellent color stability with a tiny offset of the CIE coordinates ($\Delta x=\pm0.003$, $\Delta y=\pm0.004$) and a relatively lower efficiency roll-off of 26.2% under the driving voltage varying from 3 V to 10 V.
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37 articles
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