共查询到20条相似文献,搜索用时 46 毫秒
1.
Writambhara Chakraborty Ujjal Debnath 《International Journal of Theoretical Physics》2009,48(1):232-247
In this work we have studied the possibility of obtaining cosmic acceleration in Brans-Dicke theory with varying or constant
ω (Brans-Dicke parameter) and with or without self-interacting potential, the background fluid being barotropic fluid or Generalized
Chaplygin Gas. Here we take the power law form of the scale factor and the scalar field. We show that accelerated expansion
can also be achieved for high values of ω for closed Universe. 相似文献
2.
Z. H. Cao P. Liu X. K. Meng S. C. Tang H. M. Lu 《Applied Physics A: Materials Science & Processing》2009,94(2):393-398
The crystallization of amorphous Ge films has been studied as a function of annealing temperature between 400 and 700°C by
in situ transmission electron microscopy (TEM). It is found that crystallization does not occur until the annealing temperature
reaches 650°C, which is nearly 250°C higher than the crystallization temperature in previous reports. The high crystallization
temperature and average crystal size obtained by in situ TEM are in agreement with those from Raman spectroscopy and X-ray
diffraction measurement. The kinetics analysis indicates that homogeneous nucleation is the dominant crystallization mode
and the activation energy is up to about 3.1 eV. 相似文献
3.
Gi. Schneider H. Lengfellner J. Betz K. F. Renk W. Prettl 《International Journal of Infrared and Millimeter Waves》1991,12(1):1-7
The response of polycrystalline Tl–Ba–Ca–Cu–O superconducting thin films on short laser pulses has been investigated for radiation between 10 m and 500 m wavelength. Fast signals with time constants less than 1 ns were observed for wavelengths longer than about 100 m whereas for shorter wavelengths only a bolometric signal could be detected. 相似文献
4.
L. Herrera J. Carot N. Bolivar E. Lazo 《International Journal of Theoretical Physics》2009,48(12):3537-3546
We calculate the instantaneous proper radial acceleration of test particles (as measured by a locally defined Lorentzian observer)
in a Weyl spacetime, close to the horizon. As expected from the Israel theorem, there appear some bifurcations with respect
to the spherically symmetric case (Schwarzschild) which are explained in terms of the behaviour of the superenergy, bringing
out the physical relevance of this quantity in the study of general relativistic systems. 相似文献
5.
Yuan-Hua Li Jun-Chang Liu Yi-You Nie 《International Journal of Theoretical Physics》2010,49(10):2592-2599
A new application of the genuinely entangled six-qubit state introduced recently by Tapiador et al. (J. Phys. A 42:415301,
2009) is investigated for the quantum teleportation of an arbitrary three-qubit state and for quantum information splitting (QIS)
of an arbitrary two-qubit state. For QIS, we have shown that it can be completed perfectly with two distinct measurement methods.
In our scheme, the joint Bell-state measurement and the joint multi-qubit measurement are needed. This quantum teleportation
and QIS schemes are deterministic. 相似文献
6.
Xiao-Yan Zhang Ji-Suo Wang Xiang-Guo Meng Jie Su 《International Journal of Theoretical Physics》2009,48(2):535-544
Using the coherent state representation of Wigner operator and the technique of integration within an ordered product (IWOP)
of operators, the Wigner functions of the Klauder-Perelomov coherent states (KP-CSs) for the pseudoharmonic oscillator (PHO)
are obtained and the variations of the Wigner functions with the parameters k and z are discussed. Moreover, the tomograms of the KP-CSs for the PHO are calculated by virtue of intermediate coordinate-momentum
representation in quantum optics.
Project 10574060 supported by the National Natural Science Foundation of China and project X071049 supported by Science Foundation
of Liaocheng University. 相似文献
7.
Considering the hyperfine structure and the isotopic splitting of copper active atomic levels, the temporal behavior of the
spectral structure of amplified spontaneous emission at 510.6 nm line was calculated. The spectral line shapes of 510.6 and
578.2 nm laser lines were measured and compared with the calculated results at different experimental configurations, i.e.,
without cavity mirrors, with the back mirror, and with cavity mirrors. The results of the 578.2 nm line revealed that the
mode competition was involved in the formation of laser oscillation. 相似文献
8.
L. Dunajský 《Czechoslovak Journal of Physics》1962,12(11):870-872
9.
Xue-Xiang Xu 《International Journal of Theoretical Physics》2011,50(5):1643-1655
In this work, we find that a set of energy eigenstates of the Hamiltonian of two coupled oscillators can be classified as
the atomic coherent state in the Schwinger Bosonic realization. The statistical properties of these states are also discussed
by analytically calculating their Wigner function, Husimi function and tomogram. 相似文献
10.
关于相对论问题的讨论,主要集中两点;要不要动它?怎么动?第一点似较明显,因为: 一、没有充分理由表明光速是宇宙间讯号传递的最高限,相对论必有它的局限性和适用范围,深入地对它进行分析研究无论在哲学上和学术卜都是有意义的. 二、单程光速不变,迄今并未被实验直接证明.虽然相对论的大部分(不是全部)结论已被证实. 三、如果测量出光子有静止质量或发现了超光速的运动,则现有相对论势必要改造. 事实上,弱相互作用的宇称不守恒、时间反演对称的破坏,早已发出了相对性原理被部分破坏的讯号了.秦元勋同志不满足于相对论已取得的成果,敢于动它,… 相似文献
11.
Ratul Chowdhury Ritabrata Biswas Nairwita Mazumder Subenoy Chakraborty 《International Journal of Theoretical Physics》2011,50(5):1628-1642
This paper deals in the thermodynamic properties of Einstein-Gauss-Bonnet and Einstein-Yang-Mills-Gauss-Bonnet black holes.
It exhibits the various stable and unstable phases of the black holes in these two modified gravity theories. In the first
section, that reveals the various aspects of Einstein-Gauss-Bonnet black holes, we chose to study the changes in the Hawking
Temperature with variations in the radius of event horizon (r) and charge (Q); and tried to justify them physically. Secondly in case of Einstein-Yang-Mills-Gauss-Bonnet black holes, we have attempted
to compare the changes in the various thermodynamic parameters with varying r and Q; with the Einstein-Gauss-Bonnet black holes at a macroscopic level. Here we have considered the Yang Mills tensor, electromagnetic
Lagrangian added to the action integrand. Again this very work deals in drawing out the similarities between these two types
of black holes, thereby throwing some light on the aspect of black hole stability. Later we have also introspected the effects
of the Gauss-Bonnet coupling parameter α, whose function (6αr), is added as a correction term to the black hole entropy. We have especially focused on what changes does it have upon the
nature of the plots as to whether it enhances or reduces the effect of Q on the behavior of the curves. Finally this paper has also kept an eye at estimating the stability domains of the black holes
described in these two gravity theories. 相似文献
12.
K. Pedersen M. Schiek J. Rafaelsen H.-G. Rubahn 《Applied physics. B, Lasers and optics》2009,96(4):821-826
Optical second-harmonic generation upon nanosecond laser irradiation of nanofibers grown from nonsymmetrically functionalized
para-quarter-phenylene molecules on mica surfaces is investigated in the spectral region around electronic resonances. Strong
multiphoton excited luminescence appears together with the second-harmonic signal in the spectra. It is demonstrated how the
two components can be separated by analyzing emission spectra recorded over a broad range of wavelengths around the second-harmonic
energy. Spectra of the absolute values of the second-harmonic signals are obtained for three differently functionalized molecules.
Together with supplementary measurements of the structure of the nanofiber films this forms the basis for estimation of the
second-harmonic susceptibility of the fiber materials. Values of the nonlinear susceptibilities are obtained, which are comparable
to those of well-known inorganic nonlinear optical crystals. 相似文献
13.
Takatsu H Kadowaki H Sato TJ Lynn JW Tabata Y Yamazaki T Matsuhira K 《J Phys Condens Matter》2012,24(5):052201
Neutron scattering experiments on a polycrystalline sample of the frustrated pyrochlore magnet Tb(2)Ti(2)O(7), which does not show any magnetic order down to 50 mK, have revealed that it shows condensation behavior below 0.4 K from a thermally fluctuating paramagnetic state to a spin-liquid ground state with quantum spin fluctuations. Energy spectra change from quasielastic scattering to a continuum with a double-peak structure at energies of 0 and 0.8 K in the spin-liquid state. Specific heat shows an anomaly at the crossover temperature. 相似文献
14.
Jianhong Peng Mirabbos Hojamberdiev Baowei Cao Juan Wang Yunhua Xu 《Applied Physics A: Materials Science & Processing》2011,103(2):511-516
Submicron BiFeO3 powders were successfully synthesized via a simple hydrothermal process with the assistance of mineralizer (NaOH) at 150–190°C,
using FeCl3 and Bi(NO3)3⋅5H2O as reactants. The effects of mineralizer concentration, reaction temperature and time on the phase evolution and crystal
morphology of the resulting samples were investigated. X-ray diffraction (XRD), transmission electron microscopy (TEM), thermogravimetry
and differential scanning calorimetry (TG-DSC), and vibrating sample magnetometry (VSM) were used to characterize the as-synthesized
samples. The experimental results revealed that a pure BiFeO3 phase could be formed at a temperature ranging from 170 to 190°C for 4–20 h in the presence of 0.03–0.12 M NaOH. It was found
that the mineralizer concentration, reaction temperature and time played a key role in controlling the growing speed of nuclei
and formation of BiFeO3 crystallites. The possible formation mechanisms of submicron BiFeO3 powders with different morphologies were presented. The magnetization of BiFeO3 powders showed a weak ferromagnetic behavior at room temperature. 相似文献
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17.
H. Rosu 《Il Nuovo Cimento D》1998,20(1):73-77
Summary A small collection of general facts related to DNA is presented.
The author of this paper has agreed to not receive the proofs for correction.
This work was partially supported by the CONACyT Project 4868-E9406. 相似文献
18.
Henry P. Stapp 《Foundations of Physics》2012,42(5):647-655
Robert Griffiths has recently addressed, within the framework of a ‘consistent quantum theory’ that he has developed, the
issue of whether, as is often claimed, quantum mechanics entails a need for faster-than-light transfers of information over
long distances. He argues that the putative proofs of this property that involve hidden variables include in their premises
some essentially classical-physics-type assumptions that are not entailed by the precepts of quantum mechanics. Thus whatever
is proved is not a feature of quantum mechanics, but is a property of a theory that tries to combine quantum theory with quasi-classical
features that go beyond what is entailed by quantum theory itself. One cannot logically prove properties of a system by establishing,
instead, properties of a system modified by adding properties alien to the original system. Hence Griffiths’ rejection of
hidden-variable-based proofs is logically warranted. Griffiths mentions the existence of a certain alternative proof that
does not involve hidden variables, and that uses only macroscopically described observable properties. He notes that he had
examined in his book proofs of this general kind, and concluded that they provide no evidence for nonlocal influences. But
he did not examine the particular proof that he cites. An examination of that particular proof by the method specified by
his ‘consistent quantum theory’ shows that the cited proof is valid within that restrictive version of quantum theory. An
added section responds to Griffiths’ reply, which cites general possibilities of ambiguities that might make what is to be
proved ill-defined, and hence render the pertinent ‘consistent framework’ ill defined. But the vagaries that he cites do not
upset the proof in question, which, both by its physical formulation and by explicit identification, specify the framework
to be used. Griffiths confirms the validity of the proof insofar as that pertinent framework is used. The section also shows,
in response to Griffiths’ challenge, why a putative proof of locality that he has described is flawed. 相似文献
19.
Barrow JD 《Physical review D: Particles and fields》1992,46(8):R3227-R3230