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1.
The diffraction of the wave packet of a three-level atom in a multifrequency optical radiation field is studied. A new type
of coherent beam splitter for atoms that employs the scattering of a wave packet in the field of four standing light waves
with different spatial shifts is proposed on this basis. It is shown that this interaction scheme makes it possible to obtain
large splittings (>100ℏk) of the wave packet of a three-level Λ atom in momentum space into only two coherent components. In addition, the atoms in
these coherent components are in long-lived atomic states, which substantially simplifies the experimental implementation
of such a splitter.
Pis’ma Zh. éksp. Teor. Fiz. 66, No. 6, 386–391 (25 September 1997) 相似文献
2.
The motion of an electronic wave packet in the interelectrode space of a vacuum photodetector is investigated. It is shown
that the dimensions of such a packet are of the order of 1 micron and are comparable to the optical wavelength. On interacting
with a powerful laser pulse the packet scatters a large number of photons and is deflected from its initial trajectory. Both
effects can be used to determine the parameters of an electronic wave packet.
Pis’ma Zh. éksp. Teor. Fiz. 63, No. 6, 408–411 (25 March 1996) 相似文献
3.
T. G. Talipova E. N. Pelinovsky E. Kit O. Eitan 《Radiophysics and Quantum Electronics》1999,42(4):315-319
We study the propagation of nonlinear modulated waves in weakly dispersive media within the framework of the Korteveg- de
Vries equation. It is shown that strong generation of overtones and mean flow by the modulated packet results in asymmetry
of the wave packet envelope with respect to both horizontal and vertical axes and makes the envelope skewed. The motion of
the wave packet is accompanied by the emission of low-frequency and high-frequency waves that propagate in different directions
from the packet. As a result, the mean amplitude of the wave packet decreases with distance.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 42, No. 4, pp. 354–358, April 1999. 相似文献
4.
5.
A new wave packet molecular dynamics–density functional theory (WPMD‐DFT) method is proposed for atomistic simulations of non‐ideal plasma and warm dense matter. The method is based on the WPMD approach, where the electronic exchange and correlation effects are treated using an additional energy term taken from DFT. This term is calculated by integration over the mesh values of the wave packet density. The local density approximation is implemented so far. WPMD‐DFT is meant as a replacement for the anti‐symmetrized WPMD (AWPMD) method which is more time consuming and lacks electron correlation. In this paper, we compare the results obtained by WPMD‐DFT, WPMD, AWPMD, classical molecular dynamics, and path integral Monte Carlo methods for the internal energy of the hydrogen plasma in the temperature range 10–50 kK and electron number density from 1020 to 1024 cm?3. We also demonstrate the ability to handle the simultaneous dynamics of electrons and ions by calculating the electron–ion temperature relaxation. The scalability of the WPMD‐DFT method with the number of electrons is shown for implementations in central processing unit and graphical processing unit. 相似文献
6.
The reactive ion beam mixing (IBM) of V/Al interfaces by low-energy N2+ ions at room temperature leads to the formation of V–Al–N ternary nitride thin films. The kinetics, growth mechanisms, composition
and electronic structure of those films have been studied using X-ray photoelectron spectroscopy, ultraviolet photoelectron
spectroscopy, Factor Analysis and Monte Carlo TRIDYN simulations. The comparison of experimental results with those obtained
from TRIDYN simulations suggests that the chemical reaction with the nitrogen partial pressure and processes driven by residual
defects are the rate-controlling mechanisms during the reactive IBM of V/Al interfaces. The kinetics of mixing is characterized
by two stages. During the first stage (≤4×1016 ions/cm2), the formation of vanadium nitride is observed. In the second stage, vanadium nitride is transformed into a V–Al–N ternary
nitride due to Al incorporation in the near surface region. Moreover, the V/Al ratio can be varied in a broad range, whereas
the nitrogen concentration slightly decreases with increasing the aluminium content of the film. 相似文献
7.
S. N. Molotkov 《JETP Letters》1998,68(3):263-270
A complete protocol and an optical scheme for experimental implementation of the quantum teleportation of an unknown one-photon
wave packet are proposed.
Pis’ma Zh. éksp. Teor. Fiz. 68, No. 3, 248–254 (10 August 1998) 相似文献
8.
Kazunori Kadota Takenobu Yamamoto Atsuko Shimosaka Yoshiyuki Shirakawa Jusuke Hidaka Masato Kouzu 《Journal of nanoparticle research》2011,13(12):7209-7218
The mechanism on aggregation of spindle granular particles of calcite was investigated for the carbonation of calcium hydroxide
in aqueous suspension for the purpose of controlling morphology of CaCO3. The experimental carbonation process was carried out in a semi-batch bubble column reactor under different conditions. Although,
fine rhombic nano-particles diameter ranged from 100 to 200 nm were obtained at 291 K, a higher temperature of 300 K provided
spindle granular particles with a length of 1.0–1.5 μm and a width of 0.3–0.5 μm. The average crystallite size was 28 nm for
the fine rhombic nano-particles and 43 nm for the spindle granules. Zeta potential measurement for the spindle granules indicated
that the suspension tended to be aggregated during the carbonation process. The effect of the degree of particle aggregation
on the shape of the obtained calcite particles was studied by Monte Carlo simulations. Our simulation results elucidated the
dependence of aggregation on unit particles, i.e., primary particles, on the experiment carbonation condition where the spindle
granules were formed out of the unit particles under the same condition as the experiments. In addition, the formation mechanism
of the granules was investigated by applying classical nucleation theory to the present simulations. 相似文献
9.
S. V. Meriakri 《Technical Physics》1999,44(12):1472-1476
The propagation of a microwave pulse in a ferrite thin film-substrate structure in a regime of rereflections (“ringing”) of
the acoustic component of the substrate is studied theoretically. It is shown that as a result of the interaction of microwave
pulses with the boundaries of the substrate, propagation of a microwave excitation in this system can be regarded as a propagation
of a wave packet in a periodic nonuniform medium. The basic characteristics of a propagating wave packet are obtained.
Zh. Tekh. Fiz. 69, 82–86 (December 1999) 相似文献
10.
《Physics letters. A》2002,298(1):7-17
Quantum-mechanical kicked-rotator wave packets are studied using Bohmian mechanics and a novel numerical approach. A method for extending the results into the classical regime is developed. A clear physical picture of packet behavior, including a new expression for packet spread times, emerges. 相似文献
11.
We apply a semiclassical approach to the scattering problem of a vibrational wave packet in the vicinity of a conical intersection of electronic energy surfaces and derive analytical expressions for the scattering matrix. The latter are valid when the scattering length that scales as square root(h) is small and a wave packet passes through the scattering region with a constant velocity. The analytical results are in excellent agreement with numerical simulations for a realistic set of parameters. 相似文献
12.
王德华 《原子与分子物理学报》2009,26(4):413-419
利用WKB近似和自关联函数方法,我们研究了一般幂指数中心势V(r)=rk (-20)作用下波包的回归和部分回归。对于排斥势(>0, k>0), 势是一长程势,量子化能级结构中只有一个量子数,波包的回归结构和一维幂指数势的情况类似。这一结果表明能级结构相同的体系具有相同的波包回归结构。 对于吸引势,能级结构中有两个量子数, 当 k取不同的值时,波包的回归结构不同。对于库仑吸引势,波包回归和部分回归出现; 但是对于其它的k值, 经过一段时间后,波包出现坍塌。本文的研究对于探讨里德堡原子和分子中电子运动的经典极限提供了一个新的方法。 相似文献
13.
利用WKB近似和自关联函数方法,我们研究了一般幂指数中心势V(r)=γrk (-20)作用下波包的回归和部分回归.对于排斥势(γ>0, k>0), 势是一长程势,量子化能级结构中只有一个量子数,波包的回归结构和一维幂指数势的情况类似.这一结果表明能级结构相同的体系具有相同的波包回归结构.对于吸引势,能级结构中有两个量子数, 当 k取不同的值时,波包的回归结构不同.对于库仑吸引势,波包回归和部分回归出现;但是对于其它的k值, 经过一段时间后,波包出现坍塌.本文的研究对于探讨里德堡原子和分子中电子运动的经典极限提供了一个新的方法. 相似文献
14.
K. Zhou H. P. Wang J. Chang B. Wei 《Applied Physics A: Materials Science & Processing》2011,103(1):135-137
The specific heats of liquid Ti–20at.%Al and Ti–51at.%Al alloys are determined to be 33.01±2.75 and 31.27±2.91 J mol−1 K−1 in the stable superheated and metastable undercooled states by using an electromagnetic levitation drop calorimeter. The
experimental temperature ranges are 1733–2133 K and 1511–1948 K, and maximum undercoolings of 230 (0.12 T
L) and 242 K (0.14 T
L) are achieved, respectively. On the basis of the experimental results, the specific heat dependence on the composition is
obtained for binary Ti–Al alloys. 相似文献
15.
Umamahesh Thupakula Amitav Jena Ali Hossain Khan Amit Dalui Somobrata Acharya 《Journal of nanoparticle research》2012,14(1):701
We report on the one-step synthesis of ultra narrow wurtzite CdS nanorods using bench top chemical decomposition route. The
synthesized CdS nanorods are of 1.8 nm in diameter and show major confinement along the radial dimension, which is well below
the exciton Bohr radius of bulk CdS (2.5 nm). Structural and self-assembly properties of nanorods are studied using X-ray
Diffraction (XRD) and small angle X-ray scattering (SAXS) measurements, which reveal preferred orientation of the nanorods
along <00.2> direction with 2D supercrystalline spatial distribution. The estimated nanorod dimensions from XRD is corroborated
with the transmission electron microscopy observations. UV–vis and photoluminescence spectroscopy reveals significant increase
in the band gap in comparison to bulk CdS which is further tallied with the simulations using effective mass approximation
(EMA). Formation of discrete structure of valence band and conduction band due to strongly quantum confined excitons in the
radial direction is evidenced from EMA simulation. Combination of experimental and theoretical approach helps in understanding
the structure–property relationship for ultranarrow CdS rods which might lead to nanorod based applications. 相似文献
16.
Y. Ding W. J. Fan D. W. Xu C. Z. Tong Y. Liu L. J. Zhao 《Applied physics. B, Lasers and optics》2010,98(4):773-778
We present the fabrication process and experimental results of 850-nm oxide-confined vertical cavity surface emitting lasers
(VCSELs) fabricated by using dielectric-free approach. The threshold current of 0.4 mA, which corresponds to the threshold
current density of 0.5 kA/cm2, differential resistance of 76 Ω, and maximum output power of more than 5 mW are achieved for the dielectric-free VCSEL with
a square oxide aperture size of 9 μm at room temperature (RT). L–I–V characteristics of the dielectric-free VCSEL are compared with those of conventional VCSEL with the similar aperture size,
which indicates the way to realize low-cost, low-power consumption VCSELs with extremely simple process. Preliminary study
of the temperature-dependent L–I characteristics and modulation response of the dielectric-free VCSEL are also presented. 相似文献
17.
V. P. Bykov 《JETP Letters》1996,64(8):561-566
An equation is derived for the matrix of the parameters of a small Gaussian wave packet moving in arbitrary fixed electromagnetic
fields. The equation can be used to describe the evolution of wave packets in a wide class of vacuum devices. A simple example
of the evolution of a packet in a constant magnetic field is studied.
Pis’ma Zh. éksp. Teor. Fiz. 64, No. 8, 515–520 (25 October 1996) 相似文献
18.
S. Kabi A. Ghosh 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,79(4):377-381
Electrical complex ac conductivity of the compound
Li0.9[Ni1/3Mn1/3Co1/3]O1.95 has been studied in the
frequency range 10 Hz–2 MHz and in the temperature range 93–373 K. It
has been observed that the frequency dependence of the ac conductivity obeys
a power law and the temperature dependence of the ac conductivity is quite
weak. The experimental data have been analyzed in the framework of several
theoretical models based on quantum mechanical tunneling and classical
hopping over barriers. It has been observed that the electron tunneling is
dominant in the temperature range from 93 K to 193 K. A crossover of
relaxation mechanism from electron tunneling to polaron tunneling is
observed at 193 K. Out of the several models discussed, the electron
tunneling and the polaron tunneling models are quite consistent with the
experimental data for the complex ac conductivity. The various parameters
obtained from the fits of the experimental results for the real and
imaginary parts of the conductivity to the predictions of these models are
quite reasonable. 相似文献
19.
Liang Kui Sun Hai Feng Cheng Yong Jiang Zhou Jun Wang 《Applied Physics A: Materials Science & Processing》2011,105(1):49-53
We report a metamaterial absorber (MA) with a broad absorption band in the frequency region of 2–4 GHz, whose thickness is
not limited to the quarter-wavelength. Theoretical and experimental results show that the absorber has two adjacent absorption
apexes at 2.24 and 3.46 GHz, respectively, which are both related to the electric and magnetic resonances of the metamaterial.
The absorption is over 68% in the whole wave band of 2–4 GHz provided the thickness of 4 mm. The distributions of the surface
currents and the power loss density indicate that the surface currents produced by the electric and magnetic resonances are
strongly consumed by the resistive patches. This low-frequency absorber has potential applications in many scientific and
martial fields. 相似文献
20.
M. B. Belonenko 《Russian Physics Journal》1997,40(8):799-803
Microscopic pseudospin formalism is used to examine the main laws governing the nonlinear excitation of a packet of pseudospin
waves in ferroelectrics of isomorphous KDP. The nonlinear frequency shift of the packet is determined along with its temperature
dependence. A qualitative analysis is made, of the dynamics of the “center of gravity” of the packet.
Volgograd University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 98–102, August, 1997. 相似文献