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Fisher Information of Wavefunctions: Classical and Quantum
LUO Shun-Long
Chin. Phys. Lett. 2006, 23 (12):
3127-3130
.
A parametric quantum mechanical wavefunction naturally induces parametric probability distributions by taking absolute square, and we can consider its classical Fisher information. On the other hand, it also induces parametric rank-one projections which may be viewed as density operators, and we can talk about its quantum Fisher information. Among many versions of quantum Fisher information, there are two prominent ones. The first, defined via a quantum score function, was introduced by Helstrom in 1967 and is well known. The second, defined via the square root of the density operator, has its origin in the skew information introduced by Wigner and Yanase in 1963 and remains relatively unnoticed. This study is devoted to investigating the relationships between the classical Fisher information and these two versions of quantum Fisher information for wavefunctions. It is shown that the two versions of quantum Fisher information differ by a factor 2 and that they dominate the classical Fisher information. The non-coincidence of these two versions of quantum Fisher information may be interpreted as a manifestation of quantum discord. We further calculate the difference between the Helstrom quantum Fisher information and the classical Fisher information, and show that it is precisely the instantaneous phase fluctuation of the wavefunctions.
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A Flexible Improvement for Ping-Pong Protocol
LIU Yu, HUA Sha&sup, WANG Xiao-Xin&sup, LI Yue&sup, YE Jun&sup, LI Jun
Chin. Phys. Lett. 2006, 23 (12):
3152-3154
.
A deterministic quantum communication protocol, called the ping-pong protocol, has been represented by Boström and Felbinger [Phys. Rev. Lett. 89 (2002) 187902]. Based on an entangled pair of photons, it allows asymptotically secure key distribution and quasi-secure direct communication. However, it was concluded from our previous research that the experiment realization of this protocol requires two optic paths strictly equivalent for interferometry. Here we propose an improved protocol, which is more flexible and secure for conceivable applications. Its feasibility and security are also discussed.
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Application of Electron-Shelving Detection via 423 nm Transition in Calcium-Beam Optical Frequency Standard
HUANG Kai-Kai, ZHANG Jian-Wei, YU De-Shui, CHEN Zhen-Hui, ZHUAN Wei, CHEN Jing-Biao
Chin. Phys. Lett. 2006, 23 (12):
3198-3201
.
A new scheme of small compact optical frequency standard based on thermal calcium beam with application of 423 nm shelving detection and sharp-angle velocity selection detection is proposed. Combining these presented techniques, we conclude that a small compact optical frequency standard based on thermal calcium beam will outperform the commercial caesium-beam microwave clock, like the 5071 Cs clock (from HP to Agilent, now Symmetricom company), both in accuracy and stability.
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Temperature-Insensitive Chemical Sensor with Twin Bragg Gratings in an Optical Fibre
SANG Xin-Zhu, YU Chong-Xiu, YAN Bin-Bin, MA Jian-Xin, MENG Zhao-Fang, Mayteevarunyoo T.&sup, LU Nai-Guang
Chin. Phys. Lett. 2006, 23 (12):
3202-3204
.
To reduce temperature sensitivity of the fibre Bragg grating (FBG) chemical sensor, a simple method is proposed by measuring the peak wavelength difference between an etched FBG and an un-etched one in an optical fibre. Thermal characteristics and chemical sensitivity of the sensor are experimentally investigated. The experimental results indicate that the etched FBG and the rest one have almost the same thermal response, and concentration changes of the surrounding chemical solutions can be detected by measuring the peak wavelength difference between them. The sensor has been used to measure the concentrations of propylene glycol solutions and sugar solutions, and it could detect 0.7% and 0.45% concentration changes for them with an optical spectrum analyser in resolution of 10 pm.
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Nuclear Effects in Structure Functions xF₃([x,Q²) from Charge Current Neutrino Deep Inelastic Scattering
DUAN Chun-Gui, , SHEN Peng-Nian, LI Guang-Lie,
Chin. Phys. Lett. 2006, 23 (12):
3211-3214
.
By taking advantage of the model-independent nuclear parton distributions, the structure functions xF₃(x,Q²) are calculated, in comparison with the experimental data from CCFR neutrino--nuclei charge current deep inelastic scattering. It is shown that shadowing and anti-shadowing effects occur in valence quark distributions for small and medium x regions, respectively. It is suggested that the neutrino experimental data should be employed in the future for pinning down the nuclear parton distributions.
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Structure of Di-Ω Dibaryon
DAI Lian-Rong, ZHANG Zong-Ye, YU You-Wen&sup,
Chin. Phys. Lett. 2006, 23 (12):
3215-3218
.
Previously, we extended our chiral SU(3) quark model to include the coupling between the quark and vector chiral fields [Nucl. Phys. A 727 (2003) 321]. Here we further study the structure of (ΩΩ)ST=00 dibaryon in the extended chiral SU(3) quark model by solving a resonating group method equation. The vector meson exchanges effect, hidden colour channel and colour screening effect are investigated, respectively. The results show that the (ΩΩ)ST=00 system is still the deeply bound state in the extended chiral SU(3) quark model in which the vector meson exchanges control the short-range quark--quark interaction, which is similar to the results obtained from the chiral SU(3) quark model. When the model space is enlarged by including the hidden colour channel, it is found that the energy of the hidden colour state |CC>str=-6,ST=00 is much higher than that of the (ΩΩ)ST=00 state, thus the CC channel has little effect on the binding energy of (ΩΩ)ST=00 state. When the error function confinement potential is considered, the bound state property would not change largely. Further, scalar meson mixing is considered. No matter whether S=-18° or ideal mixing is taken, (ΩΩ)ST=00 state is still a bound state.
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Search for Double γ-Vibrational Bands in Neutron-Rich 105Mo Nucleus
DING Huai-Bo&sup, ZHU Sheng-Jiang, J. H. Hamilton&sup, A. V. Ramayya&sup, J. K. Hwang&sup, Y. X. Luo, J. O. Rasmussen&sup, I. Y. Lee&sup, CHE Xing-Lai&sup, CHEN Yong-Jing&sup, LI Ming-Liang
Chin. Phys. Lett. 2006, 23 (12):
3222-3225
.
Levels in the neutron-rich 105Mo nucleus have been investigated by observing prompt γ-rays following the spontaneous fission fragments of 252Cf with the Gammasphere detector array. The yrast band has been confirmed and updated. The other two collective bands with the band head levels at 870.5 and 1534.6 keV are newly observed, and they are suggested as the candidates for one-phonon K=9/2 and two-phonon K=13/2 double γ-vibrational bands, respectively. Systematic characteristics of these bands have been discussed.
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Effects of Substrate Temperature on Helium Content and Microstructure of Nanocrystalline Titanium Films
PANG Hong-Chao&sup, LUO Shun-Zhong&sup, LONG Xing-Gui&sup, AN Zhu&sup, LIU Ning&sup, DUAN Yan-Min&sup, WU Xing-Chun&sup, YANG Ben-Fu&sup, WANG Pei-Lu&sup, ZHENG Si-Xiao
Chin. Phys. Lett. 2006, 23 (12):
3238-3241
.
Helium-charged nanocrystalline titanium films have been deposited by He--Ar magnetron co-sputtering. The effects of substrate temperature on the helium content and microstructure of the nanocrystalline titanium films have been studied. The results indicate that helium atoms with a high concentration are evenly incorporated in the deposited titanium films. When the substrate temperature increases from 60°C to 350°C while the other deposition parameters are fixed, the helium content decreases gradually from 38.6 at.% to 9.2 at.%, which proves that nanocrystalline Ti films have a great helium storage capacity. The 2θ angle of the Bragg peak of (002) crystal planes of the He-charged Ti film shifts to a lower angle and that of (100) crystal plane is unchanged as compared with that of the pure Ti film, which indicates that the lattice parameter c increases and a keeps at the primitive value. The grain refining and helium damage result in the diffraction peak broadening.
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Exact Timing of Returned Molecular Wavepacket
ZHANG Zhe, WANG Ting-Ying, ZHANG Gui-Zhong, W.T. Hill III
Chin. Phys. Lett. 2006, 23 (12):
3242-3244
.
An ionizing wavepacket of electron will re-visit its parent molecular ion during photoionization by strong laser field. This scenario is associated with physical concepts such as molecular re-scattering/collision, interference, diffraction, molecular clock, and generation of XUV light via high-order harmonic generation. On the workbench of a reduced dimensionality model of molecular hydrogen ions irradiated by laser pulse of 0.01--10.0 a.u. intensities, one-cycle pulsewidth, and 800 nm wavelength, by deploying a momentum operator on the time-dependent wavefunction of an ionizing wavepacket, we can determine, in a precise manner, the exact time instant for the re-visiting electron to come back to the cation position. The time value is 57.6% of an optical cycle of the exciting laser pulse. This result may be useful in attosecond pump--probe experiments or molecular clock applications.
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Spectrum Simulation of Li-Like Aluminium Plasma
PENG Feng, JIANG Gang, ZHU Zheng-He
Chin. Phys. Lett. 2006, 23 (12):
3245-3248
.
X-ray emission spectra for L-shell of Li-like aluminium ions are simulated by using the flexible atomic code based on the collisional radiative model. Atomic processes including radiative recombination, dielectronic recombination, collisional ionization and resonance excitation from the neighbouring ion (Al9+ and Al11+) charge states of the target ion (Al10+) are considered in the model. In addition, the contributions of different atomic processes to the x-ray spectrum are analysed. The results show that dielectronic recombination, radiative recombination, collisional ionization and resonance excitation, other than direct collisional excitation, are very important processes.
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Measurements of AIM for Visible Wavelength Based on Individual Eye Model
WANG Wei, WANG Zhao-Qi, WANG Yan, ZUO Tong, ZHAO Kan-Xing
Chin. Phys. Lett. 2006, 23 (12):
3263-3266
.
We measure and calculate the aerial image modulation (AIM) of human retina for visible wavelengths based on the individual eye model. By employing the optical design software ZEMAX, we obtain the modulation transfer function (MTF) of human eye in visible wavelengths. Using CSV-1000 and VAF-1000, the contrast sensitivity function (CSF) and the visual acuity (VA) for the same eye are measured. Then the AIM of human retina could be acquired by the relations between MTF and CSF and between MTF and VA. The AIM of human retina is independent of MTF, and the values of AIM for normal eyes (without retina disease) are similar, so the assembly average for large numbers of normal eyes can be a standard AIM curve, which is helpful for the diagnosis of diseases in the retina system.
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High-Power Extracavity Pulse Compression in Solid Materials
LI Xiao-Fang, CHEN Xiao-Wei, JIANG Yong-Liang, LIU Jun, ZENG Zhi-Nan, LI Ru-Xin, XU Zhi-Zhan
Chin. Phys. Lett. 2006, 23 (12):
3278-3280
.
A novel technique for high-power extracavity pulse compression with a nonlinear solid material is demonstrated. Before spectral broadening by self-phase modulation in the solid material, a short filament generated in argon is used as a spatial filter, which works for a uniform spectrum broadening over the spatial profile. Compensated by chirped mirrors, a 15-fs pulse is generated from a 32-fs input laser pulse. A total transmission larger than 80% after the solid material is achieved.
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A Wide-Band Thulium-Doped Silica Fibre Amplifier
DU Ge-Guo, LI Da-Jun, LI Hong-Wei, MAI Bing-Liang, YOU Jie-Shun, RUAN Shuang-Chen
Chin. Phys. Lett. 2006, 23 (12):
3291-3293
.
We investigate a silica-based thulium-doped fibre amplifier, which is a promising candidate for an amplifying device in the S band, in detail using a single wavelength upconversion pumping scheme centred at 1064 nm. Our experimental results show that in terms of gain and noise figure, the bi-directional pumping scheme is the best one in the three pumping schemes, named forward, backward and bi-directional pumping schemes. The amplifier has a gain not only in the S band, but also in the C band, even in the L band. The gain is above 3 dB from 1525 nm to 1580 nm with a peak of 7.5 dB.
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Radiation Acoustic Field of a Linear Phased Array on a Cylindrical Surface
DENG Fang-Qing, ZHANG Bi-Xing, WANG Dong, SONG Gong-Pu
Chin. Phys. Lett. 2006, 23 (12):
3297-3300
.
A new linear ultrasonic phased array fixed on a cylindrical surface is designed. This kind of the cylindrical phased array can meet the specific requirements of the application in testing pipe quality inside pipes. Using the transducer, we can not only avoid mechanical rotating but also test the quality of any point in a pipe by ultrasonic phase array technology. The focused acoustic field distributions in the axial, radial and tangential directions of the transducer are investigated theoretically by numerical simulation. The energy flux density, the width of the main lobe, the imaging resolution, the grating lobe elimination and other characteristics are analysed. The effect of the focal distance, effective aperture, transducer radius, number of total element, and steering angle on the acoustic field distribution is also studied thoroughly. Many important results are obtained.
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Magnetic Properties of Hf0.8Ta0.2(Fe0.97A0.03)2 (A=Al, Co, Mn) Systems
HUANG Yan-Jun, JIANG Zhong-Ying, CHEN Nan, HAN Zhi-Da, LI Shu-Zhen, HSIA Yuan-Fu
Chin. Phys. Lett. 2006, 23 (12):
3309-3312
.
Mössbauer studies on the effect of substitution with 3% Al, Co, Mn atoms in the intermetallic compound of Hf0.8Ta0.2Fe₂ are reported. The Al substitution leads to increase of the FM-AFM transition temperature and to decrease of the AFM-PM transition temperature. The Co substitution leads to disappearance of the FM state, only showing some FM impurity component, while Mn substituted compound indicates coexistence of FM and AFM states at low temperature. The phenomena imply complex itinerant electron properties in these magnetic systems.
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Numerical Simulation of Dust Void Evolution in Complex Plasmas with Ionization Effect
LIU Yue, WANG Zheng-Xiong, WANG Xiao-Gang,
Chin. Phys. Lett. 2006, 23 (12):
3313-3315
.
We develop the nonlinear theory of dust voids [Phys. Rev. Lett. 90 (2003) 075001], focusing particularly on effects of the ionization, to investigate numerically the void evolution under cylindrical coordinates [Phys. Plasmas 13 (2006) 064502]. The ion velocity profile is solved by a more accurate ion motion equation with the ion convection and ionization terms. It is shown that the differences between the previous result and the one obtained with ionizations are significant for the distributions of the ion and dust velocities, the dust density, and etc., in the void formation process. Furthermore, the ionization can slow down the void formation process effectively.
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Gaseous Hydrogenation and Its Effect on Thermal Stability of Mg63Ni22Pr15 Metallic Glass
DU Yu-Lei, DENG Yan-Hui, XU Feng, CHEN Guang,
CHEN Guo-Liang, ZHANG Qing-An
Chin. Phys. Lett. 2006, 23 (12):
3320-3322
.
Mg63Ni22Pr15 metallic glasses are produced by a single roller melt-spinning technique. The hydrogen absorption and desorption capacities are respectively 0.38 and 0.14 wt.% at 313 K obtained by pressure-composition isotherm. The amorphous structure is found to be retained after gaseous hydrogenation. The glass transition temperature, the onset crystallization temperature, and the crystallization temperature of the hydrogenated Mg63Ni22Pr15 metallic glass are 550, 570 and 577 K, respectively, much higher than the corresponding values of 440, 470 and 499 K of the as-quenched sample. This means that dramatic enhancement of thermal stability occurs in Mg63Ni22Pr15 metallic glass due to hydrogenation.
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First-Principles Study on the Electronic Structures for Y3+:PbWO₄ Crystals
CHEN Teng, LIU Ting-Yu, ZHANG Qi-Ren, LI Fang-Fei, YI Zhi-Jun, TIAN Dong-Sheng, ZHANG Xiu-Yan
Chin. Phys. Lett. 2006, 23 (12):
3323-3326
.
The possible defect models of Y3+:PbWO₄ crystals are discussed by defect chemistry and the most possible substituting positions of the impurity Y3+ ions are studied by using the general utility lattice program (GULP). The calculated results indicate that in the lightly doped Y3+:PWO crystal, the main compensating mechanism is [2YPb++VPb2-], and in the heavily doped Y3+:PWO crystal, it will bring interstitial oxygen ions to compensate the positive electricity caused by YPb+, forming defect clusters of [2YPb++Oi2-] in the crystal. The electronic structures of Y3+:PWO with different defect models are calculated using the DV-X method. It can be concluded from the electronic structures that, for lightly doped cases, the energy gap of the crystal would be broadened and the 420 nm absorption band will be restricted; for heavily doped cases, because of the existence of interstitial oxygen ions, it can bring a new absorption band and reduce the radiation hardness of the crystal.
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Optical Waveguide Formed in RbTiOPO4 Crystal by 6.0 MeV O3+ Implantation
JIAO Yang, WANG Ke-Ming, WANG Xue-Lin, CHEN Feng,
WANG Lei, WANG Liang-Ling, LU Qing-Ming, MA Hong-Ji, NIE Rie
Chin. Phys. Lett. 2006, 23 (12):
3328-3330
.
A planar optical waveguide was formed in RbTiOPO4; crystal by 6.0-MeV oxygen ion implantation with the dose of 2×1015 ions/cm² at room temperature. Annealing at 200°C for 30 min in air is performed to improve the thermal stability of the waveguide. The dark modes of the waveguide are measured at wavelengths 633 and 1539 nm, respectively. The refractive index profiles in the guiding layer are reconstructed by using the reflectivity calculation method. TRIM'98 code was carried out to simulate the damage profiles caused by the implantation process to obtain a better understanding of the waveguide formation.
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Micro-Photoluminescence Confocal Mapping of Single V-Grooved GaAs Quantum Wire
HUANG Shao-Hua, CHEN Zhang-Hai, BAI Li-Hui, SHEN Xue-Chu, H. H. Tan&sup, L. Fu&sup, M. Fraser&sup, C. Jagadish&sup,
Chin. Phys. Lett. 2006, 23 (12):
3341-3344
.
We perform the micro-photoluminescence measurement at low temperatures and a scanning optical mapping with high spatial resolution of a single V-grooved GaAs quantum wire modified by the selective ion-implantation and rapid thermally annealing. While the mapping shows the luminescences respectively from the quantum wires and from quantum well areas between quantum wires in general, the micro-photoluminescence at liquid He temperatures reveals a plenty of spectral structures of the PL band for a single quantum wire. The spectral structures are attributed to the inhomogeneity and non-uniformity of both the space structure and compositions of real wires as well as the defects nearby the interface between quantum wire and surrounding quantum well structures. All these make the excitons farther localized in quasi-zero-dimensional quantum potential boxes related to these non-uniformity and/or defects. The results also demonstrate the ability of micro-photoluminescence measurement and mapping for the characterization of both opto-electronic and structural properties of real quantum wires.
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Critical Scaling of Extended Power Law I - V Isotherms near Vortex Glass Transition
HU Xiang, HE Li, NING Zhen-Hua, CHEN Kai-Xuan, YIN Lan, LU Guo, XU Xiao-Lin, GUO Jian-Dong, WANG Fu-Ren,
LI Chuan-Yi, YIN Dao-Le
Chin. Phys. Lett. 2006, 23 (12):
3349-3351
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In view of the question about the vortex glass theory of the freezing of disordered vortex matter raised by recent experimental observations, we reinvestigate the critical scaling of high Tc superconductors. It is found that the dc current-voltage characteristic of mixed state superconductors has a general form of extended power law which is based on the Ginzburg--Landau (GL) functional in the similar way as the vortex glass theory. Isotherms simulated from this nonlinear equation fit the experimental I-V data of Strachan et al. [Phys. Rev. Lett. 87 (2001) 067007]. The puzzling question of the derivative plot for the I-V curves and the controversy surrounding the values of critical exponents are discussed.
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Characteristics of High In-Content InGaN Alloys Grown by MOCVD
ZHU Xue-Liang, GUO Li-Wei, YU Nai-Sen, PENG Ming-Zeng, YAN Jian-Feng, GE Bing-Hui, JIA Hai-Qiang,
CHEN Hong, ZHOU Jun-Ming
Chin. Phys. Lett. 2006, 23 (12):
3369-3372
.
InN and In0.46Ga0.54N films are grown on sapphire with a GaN buffer by metalorganic chemical vapour deposition (MOCVD). Both high resolution x-ray diffraction and high resolution transmission electron microscopy results reveal that these films have a hexagonal structure of single crystal. The thin InN film has a high mobility of 475 cm2V-1s-1 and that of In0.46Ga0.54 is 163 cm2V-1s-1;. Room-temperature photoluminescence measurement of the InN film shows a peak at 0.72 eV, confirming that a high quality InN film is fabricated for applications to full spectrum solar cells.
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Design and Fabrication of 1.06 μm Resonant-Cavity Enhanced Reflective Modulator with GaInAs/GaAs Quantum Wells
YANG Xiao-Hong, HAN Qin, NI Hai-Qiao, HUANG She-Song,
DU Yun, PENG Hong-Ling, XIONG Yong-Hua, NIU Zhi-Chuan,
WU Rong-Han
Chin. Phys. Lett. 2006, 23 (12):
3376-3379
.
A resonant-cavity enhanced reflective optical modulator is designed and fabricated, with three groups of three highly strained InGaAs/GaAs quantum wells in the cavity, for low voltage and high contrast ratio operation. The quantum wells are positioned in antinodes of the optical standing wave. The modulator is grown in a single growth step in an molecular beam epitaxy system, using GaAs/AlAs distributed Bragg reflectors as both the top and bottom mirrors. Results show that the reflection device has a modulation extinction of 3 dB at -4.5 V bias.
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Topological Properties of Urban Public Traffic Networks in Chinese Top-Ten Biggest Cities
LI Ping, XIONG Xing, QIAO Zhong-Liang, YUAN Gang-Qiang,
SUN Xing, WANG Bing-Hong
Chin. Phys. Lett. 2006, 23 (12):
3384-3386
.
We investigate the topological characteristics of complex networks as exemplified by the urban public traffic network (UPTN) in Chinese top-ten biggest cities. It is found that the UPTNs have small world behaviour, by the examination of their topological parameters. The quantitative analysis of the transport efficiency of the UPTNs reveals their higher local efficiency El and lower global efficiency Eg, which coincide well with the status quo of those Chinese cities still at their developing stage. Furthermore, the topological properties of efficiency in the UPTNs are also examined, and the findings indicate that, on the one hand, the UPTNs show robustness to random attacks and frangibility to malicious attacks on a global scale; on the other hand, the interrelation between UPTN efficiency and network motifs deserves our attention. The motifs which interrelate the UPTN efficiency are always triangular-formed patterns, e.g. motifs ID 238, ID 174 and ID 102, etc.
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74 articles
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