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Entanglement Manipulation for a Two-Mode Squeezed Vacuum State
ZHOU Qing-Ping, , FANG Mao-Fa, LIU Xiao-Juan, CHEN Xiao-Mei, WU Qin
Chin. Phys. Lett. 2004, 21 (9):
1692-1694
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By numerically analysing the entropy of entanglement of the output state from a Mach--Zehnder interferometer for the two-mode squeezed vacuum state input, it is found that if the internal phase shift of the interferometer is adjusted to the value of 0 or π, the entangling characteristic of the input state is efficiently preserved at the output. If the internal phase shift is tuned to the value of π, the two-mode squeezed vacuum state is completely disentangled at the output of the setup. If the internal phase shift deviates from the above values, the input state is degraded into a partially entangled output state. Based on these results, a method for optically realizing the entanglement preservation, entanglement degradation, and disentanglement via the interferometer is obtained.
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Possible Experimental Evidence of a Moderate Proton Halo in 29S
LIU Zu-Hua, RUAN Ming, ZHAO Yao-Lin, ZHANG Huan-Qiao, YANG Feng, MA Zhong-Yu, LIN Cheng-Jian, CHEN Bao-Qiu, WU Yue-Wei, ZHAN Wen-Long, GUO Zhong-Yan, XIAO Guo-Qing, XU Hu-Shan, SUN Zhi-Yu, LI Jia-Xing, CHEN Zhi-Qiang
Chin. Phys. Lett. 2004, 21 (9):
1711-1713
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The total reaction cross sections (TRCSs) of 29S+28Si have been measured at intermediate energies. An obvious enhancement in TRCS of 29S is observed as compared with its neighbouring nuclei. The TRCSs of 29S+28Si are calculated with the modified Glauber theory in the optical limit and few-body approaches. The different factor d as a possible measure of halo appearance is deduced from the experimental and theoretical data. It is well accepted that 27P is a proton halo nucleus. Although not as anomalous as 27P, the different factor d of 29S is obviously larger than that of its neighbouring isotones of N=13. This result indicates that a moderate proton halo may exist in 29S nucleus. We calculate the total reaction cross sections for 29S with the modified Glauber theory as a function of incident energy and compare the results with those for 27Si which is a core nucleus of 29S. The measured TRCSs of 27Si+28Si can be described to be satisfactory by the modified Glauber theory of the optical limit approach. Although a diffused nuclear density distribution is used, the theories still inadequately predict the experimental TRCSs of 29S+28Si, which further indicates the possibility of proton halo in29S.
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Up-Conversion Luminescence of a High Soluble Zinc Phthalocyanine--Epoxy Derivative
SHEN Yue, XIA Yi-Ben, CHEN Jing-Wei, GU Feng, JIAO Feng-Hua, ZHANG Jian-Cheng
Chin. Phys. Lett. 2004, 21 (9):
1717-1719
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Synthesis and photoelectric properties of a high soluble zinc phthalocyanine--epoxy derivative are investigated. The derivative can be solubilized in convenient solvents, such as CH3OH, CH3CH2OH and H2O. The fluorescence and UV-visible analyses indicate that the ZnPc--epoxy derivative still maintains the plane structure which comes from Zn(4,4',4'',4''' -ta)Pc and the derivative has obvious up-conversion luminescence in room temperature. The up-conversion luminescence can be explained by the selection rule depending on the two-photon absorption.
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Ultrafast Optical Response from a Novel Tri-Branched Copolymer
LI Bo, MI Jun, MENG Fan-Shun, TIAN He, QIAN Shi-Xiong
Chin. Phys. Lett. 2004, 21 (9):
1730-1733
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A novel tri-branched copolymer is synthesized to show strong two-photon absorption and intense two-photon absorption induced fluorescence emission under the excitation of the femtosecond laser pulses at wavelength of 800nm. The dynamics of the excited state was measured by the pump-probe technique. In a one-colour pump-probe experiment at 800nm, there was an ultrafast transient absorption, followed by other two relaxation processes. The two-photon absorption process could be one origin for this ultrafast photoabsorption signal, which was further proven by two-colour pump--probe experiments. The other two decaying processes in the transient absorption dynamics have lifetime of about 15ps and 129ps, which reflect the intraband vibrational relaxation and the decay of two-photon excited state, respectively.
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Physical Properties of Novel Lead-Bismuthate Glasses with Large Transmitting Windows
SUN Hong-Tao, ZHANG De-Bao, XU Shi-Qing, DAI Shi-Xun, HU Li-Li, JIANG Zhong-Hong
Chin. Phys. Lett. 2004, 21 (9):
1759-1759
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Novel lead-bismuthate glasses with low OH concentration have been obtained in the Bi2O3-PbO-SrO system. The role of the different components in the glass formation has been explored from the density, refractive index measurements, indicating that the physical properties are mainly affected by Bi2O3 and PbO contents. The densities and refractive indices of these glasses are in the ranges of 7.639--7.699g/cm3 and 2.47--2.94, respectively. A wide transmitting window from visible to infrared (IR) regions and good thermal stability for some compositions of these glasses have been observed, which make them appealing candidates for different optical applications such as upconverting phosphors, new laser materials, optical waveguides and crystal-free fibre drawing.
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Thermal Stability and Spectroscopic Properties of New Er3+/Yb3+-Codoped Tellurite Glasses
GAO Yuan, NIE Qiu-Hua, XU Tie-Feng, SHEN Xiang
Chin. Phys. Lett. 2004, 21 (9):
1799-1801
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A series of new Er3+/Yb3+-codoped 70TeO2--5Li2O--(25-x)B2O3--xGeO2 (TLBG, x=0, 5, 10, 15, 20mol%) glasses are prepared. The thermal stability and spectroscopic properties of TLBG glasses are studied. It is found that these glasses have the better thermal stability ((Tx-Tg)>150 °C) compared with 75TeO2--20ZnO--5Na2O (TZN) glass. The fluorescence full width at half maximum (FWHM) is about 77nm, while the emission intensity and the quantum efficiency of the 4I13/2 level of Er3+ increase with the increasing GeO2 content. The maximum quantum efficiency and stimulated emission cross-section of Er3+ calculated from the McCumber theory are 93.82% and 9.0×10-21cm2, respectively. The products of FWHM and σpeake of Er3+ in TLBG glasses are larger than those in other reported glasses. The obtained data indicate that this kind of TLBG glasses is a promising candidate host material for Er3+-doped broadband amplifiers.
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Electrical Characteristics and Microstructures of Sm2O3-Doped Bi4Ti3O12 Ceramics
CHEN Min, WANG Yu, LIU Zu-Li, DONG Liang, YANG Xin-Sheng, YAO Kai-Lun,
Chin. Phys. Lett. 2004, 21 (9):
1811-1814
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We investigate the electrical properties of Sm-doped Bi4-xSmxTi3O12 (BST) ceramics prepared by a conventional electroceramic technique. The x-ray diffraction analysis reveals the Bi-layered perovskite structure in all samples. The SEM micrographs show randomly oriented and plate-like morphology. For the samples with x=0.4 and 1.0, the current--voltage characteristics exhibit negative differential resistance behaviour and the P--V hysteresis loops are characterized by large leakage current, whereas for the samples with x=0.6 and 0.8, the current--voltage characteristics show simple ohmic behaviour and the P--V hysteresis loops are of the saturated and undistorted hysteresis. The remanent polarization and coercive field of the BST ceramic with x=0.8 are above 32μC/cm2 and 70kV/cm, respectively.
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Investigation of the Size Effect on the Giant Dielectric Constant of CaCu3Ti4O12 Ceramic
CHEN Kai, LI Wei, LIU Yun-Fei, BAO Peng, LU Xiao-Mei, ZHU Jin-Song
Chin. Phys. Lett. 2004, 21 (9):
1815-1818
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Cubic perovskite-related ceramic CaCu3Ti4O12 has a very high dielectric constant larger than 10000 in the kilohertz frequency region. It is almost constant in the 100--600K region. The ceramic compounds were prepared by conventional solid-state reaction at different sintering temperatures 1040°C(C04),1060°C(C06), 1080°C(C08), and 1100°C(C10). Impedance spectroscopy on CaCusTi4O12 ceramics demonstrates that they are electrically heterogeneous and consist of semi-conducting grains with insulating grain boundaries. It is shown that C06 is the most suitable one for device applications. Surface observation and analysis of the grain-boundary-grained structure were carried out by using scanning electron microscopy, which confirms that the samples have clearly different crystal grain sizes and C06 has a larger grain size of about 20μm. Compared to the dielectric relaxation spectroscopy, the mechanical relaxation spectroscopy on C06 was performed and a mechanical loss peak was found, which was attributed to the thermally activated behaviour being immanent in the grains.
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GaN Growth with Low-Temperature GaN Buffer Layers Directly on Si(111) by Hydride Vapour Phase Epitaxy
YU Hui-Qiang, CHEN Lin, ZHANG Rong, XIU Xiang-Qian, XIE Zi-Li, YE Yu-Da, GU Shu-Lin, SHEN Bo, SHI Yi, ZHENG You-Dou
Chin. Phys. Lett. 2004, 21 (9):
1825-1827
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GaN films are grown on Si(111) with low-temperature GaN (LT-GaN) layers as buffer layers by hydride vapour phase epitaxy (HVPE). The deposition temperature of the LT-GaN layers is changed from 400 to 900°C. When the LT-GaN layer is deposited at 600°C, GaN films show only c-oriented GaN (0002) and have the band edge emission at 365nm with no yellow luminescence bands. The results indicate that the LT-GaN layer can effectively block the unexpected Si etching by reactive gas during the GaN growth. However, the surface roughness of these GaN films grown on Si(111) is larger than that of GaN films on c-plane sapphire.
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Highly Efficient Dye-Sensitized Solar Cells Using a Composite Electrolyte Consisting of LiI(CH3OH)4-I2, SiO2 Nano-Particles and an Ionic Liquid
XUE Bo-Fei, WANG Hong-Xia, HU Yong-Sheng, LI Hong, WANG Zhao-Xiang, MENG Qing-Bo, HUANG Xue-Jie, CHEN Li-Quan, O. Sato, A. Fujishima
Chin. Phys. Lett. 2004, 21 (9):
1828-1830
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Solid-state electrolyte LiI(CH3OH)4-I2 is used in dye-sensitized solar cells (DSSCs). The DSSCs using only the LiI(CH3OH)4-I2 electrolyte show very poor performance due to the quick crystal growth of LiI(CH3OH)4. In order to improve the performance of DSSCs, we prepare a composite electrolyte by adding SiO2 nano-particles and an ionic liquid, 1-methyl-3-ethylimidazolium iodide, into the original solid-state electrolyte. High efficiency of 4.3% is achieved by applying this composite electrolyte to DSSCs.
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Influence of Growth Temperature and Trimethylindium Flow of InGaN Wells on Optical Properties of InGaN Multiple Quantum-Well Violet Light-Emitting Diodes
LI Zhong-Hui, , YU Tong-Jun, YANG Zhi-Jian, TONG Yu-Zhen, ZHANG Guo-Yi, FENG Yu-Chun, GUO Bao-Ping, NIU Han-Ben
Chin. Phys. Lett. 2004, 21 (9):
1845-1847
.
An InGaN multiple-quantum-well (MQW) violet-light-emitting diode (LED) is grown by low-pressure metalorganic chemical vapour deposition. It is found that photoluminescence wavelength of the InGaN MQW violet LED is lengthened with increasing growth temperature and with the increasing trimethylindium flow of the InGaN wells. The electroluminescence peak wavelength of the violet LED are about 401nm with full width at half maximum of 14nm, and the output power in injection current of 20mA at room temperature is 4.1mW.
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54 articles
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