共查询到20条相似文献,搜索用时 15 毫秒
1.
Zoltán Donkó Peter Hartmann Ranna U. Masheyeva Karlygash N. Dzhumagulova 《等离子体物理论文集》2020,60(8):e201900197
We investigate via molecular dynamics simulations the propagation of solitons in a two-dimensional many-body system characterized by Yukawa interaction potential. The solitons are created in an equilibrated system by the application of electric field pulses. Such pulses generate pairs of solitons, which are characterized by a positive and negative density peak, respectively, and which propagate into opposite directions. At small perturbation, the features propagate with the longitudinal sound speed, from which an increasing deviation is found at higher density perturbations. An external magnetic field is found to block the propagation of the solitons, which can, however, be released upon the termination of the magnetic field and can propagate further into directions that depend on the time of trapping and the magnetic field strength. 相似文献
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Xiao-Fang Ouyang 《International Journal of Theoretical Physics》2014,53(3):754-758
We investigate spin squeezing in optomechanical system. We first derive the mean spin direction, the optimally squeezed angle and then calculate the spin squeezing parameter, which is independent of the frequency of the cavity field. The lager coupling strength more rapidly generates spin squeezed state, but the corresponding spin squeezed state maintains shorter time interval. 相似文献
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We investigate quantum coherence and spin squeezing in optomechanical system. We first determine the mean spin direction, the optimally squeezed angle and then calculate the first-order temporal correlation function, the squeezing parameter, which are independent of the frequency of the cavity field. The lager coupling strength more rapidly generates spin squeezed state, but the corresponding spin squeezed state maintains shorter time interval. 相似文献
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D. L. Hovhannisyan V. O. Chaltykyan A. S. Martirosyan 《Journal of Contemporary Physics (Armenian Academy of Sciences)》2009,44(4):183-190
Results of theoretical study of nonlinear propagation of a few-cycle laser pulse in a fused quartz are presented. With use of the finite-difference technique we have integrated numerically the system of the nonlinear Maxwell equations describing the propagation of a linearly polarized pulse at the central wavelength in the range of zero dispersion (λ0 = 1.27 μm) and duration 20 fs. The evolution of the laser pulse spectrum is calculated and the dependences of the shift of the spectral peak on both the strength of electric field and medium length are obtained. 相似文献
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激光在大气中长距离传输时所产生的相位不连续点的数目与位置不仅与大气湍流和传输距离有关,而且与传输的激光波长有关。由于对主激光进行补偿的相位是从畸变的信标光场中获得的,当畸变光场中出现相位不连续点后,畸变光场的相位由连续相位部分和不连续相位部分组成,不连续相位部分直接与畸变光场中出现的相位不连续点的数密度和其所在的位置有关,一般情况下,主激光的波长与信标光的波长是不同的,因此当主激光的波长一定后,为了对不连续相位进行补偿,以便提高强湍流效应条件下的自适应光学校正能力,必须要考虑合作信标的波长。计算结果表明,考虑了不连续相位的影响后,虽然对主激光的校正效果有所改善,但对不同波长的信标改善的效果并不相同,只有信标光波长稍长于主激光的波长时,校正效果才有明显的改善。 相似文献
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With reference to squeezed states, we analyse the noise performances of the basic detection schemes in fibre telecommunications and interferometry. We have developed a semiclassical approach that allows us to translate the quantum mechanical formalism into synthetic expressions and rules only involving directly measurable physical quantities. As a result, we find that in the telecommunication field squeezed states do not allow significant improvements in system performances: in practice, the signal-to-noise ratio cannot be increased in standard detection schemes, both direct and coherent, by squeezing either the signal (because of propagation losses) or by the local oscillator. On the contrary, a significant improvement can be obtained in interferometric measurements if squeezed vacuum is coupled into the normally unused beamsplitter port. 相似文献
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Neutrino-photon processes, forbidden in vacuum, can take place in the presence of a thermal medium and/or an external electro-magnetic
field, mediated by the corresponding charged leptons (real or virtual). Such interactions affect the propagation of neutrinos
through a magnetized plasma. We investigate the neutrino-photon absorptive processes, at the one-loop level, for massless
neutrinos in a weakly magnetized plasma. We find that there is no correction to the absorptive part of the axial-vector-vector
amplitude due to the presence of a magnetic field, to the linear order in the field strength. 相似文献
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双频探测光场在二能级Dressed原子系统中的稳态传播,在一定条件下可以转化成一个自由传播问题,和一个等效场在二能级放大原子介质中的稳态传播问题,光场与Dressed原子之间独特的耦合,导致一种联合传播. 相似文献
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We analyze the propagation of a pair of quantized fields inside a medium of three-level atoms in a Lambda configuration. We calculate the stationary quadrature noise spectrum of the field, in the case where the probe field is in a squeezed state and the atoms show electromagnetically induced transparency. We find an oscillatory transfer of the initial quantum properties between the probe and pump fields which is most strongly pronounced when both fields have comparable intensities. This implies that the quantum state measured after propagation can be completely different from the initial state, even though the mean values of the field are unaltered. 相似文献
13.
Properties of field quantum entropy evolution in the Jaynes--Cummings model with initial squeezed coherent states field 下载免费PDF全文
The properties of the field quantum entropy evolution in a system of
a single-mode squeezed coherent state field interacting with a
two-level atom is studied by utilizing the complete quantum theory,
and we focus our attention on the discussion of the influences of
field squeezing parameter $\gamma $, atomic distribution angle
$\theta $ and coupling strength $g$ between the field and the atom
on the properties of the evolution of field quantum entropy. The
results obtained from numerical calculation indicate that the
amplitude of oscillation of field quantum entropy evolution
decreases with the increasing of squeezing parameter $\gamma $, and
that both atomic distribution angle $\theta $ and coupling strength
$g$ between the field and the atom can influence the periodicity of
field quantum entropy evolution. 相似文献
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本文利用推广的Jaynes-Cummings哈密顿量的第n个子空间的完备集研究二能级系统的双光子辐射的量子统计性质,求出了场方差的一般表达式,得到了任意初态的最佳压缩条件和最佳压缩量,并分析了最佳压缩态的时间演化。作为例子,讨论了初态为热平衡分布的裸原子系统的压缩行为的时间演化,显示了压缩对于温度、失谐量、耦合劲度等参量的依赖关系,并给出了压缩条件的解析形式及数值曲线。最后指出了上述压缩的物理图象。
关键词: 相似文献
17.
Yuan Li Yusheng Zhou Yong Wang Qiang Ling Bing Chen Yan Dou Wei Zhang Weiqing Gao Zhiqiang Guo Junxiang Zhang 《Physics letters. A》2018,382(12):818-822
We theoretically study the squeezed probe light passing through a double electromagnetically induced transparency (DEIT) system, in which a microwave field and two coupling lights drive a loop transition. It is shown that the output squeezing can be maintained in both two transparency windows of DEIT, and it can also be manipulated by the relative phase of the three driving fields. The influence of the intensity of applied fields and the optical depth of atoms on the squeezing is also investigated. This study offers possibilities to manipulate the squeezing propagation in atomic media by the phase of electromagnetic fields. 相似文献
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The entropy squeezing properties for a two-level
atom interacting with a two-mode field via two different competing transitions
are investigated from a quantum information point of view. The influences
of the initial state of the system and the relative coupling strength between the atom and the field
on the atomic information entropy squeezing are discussed. Our results show that
the squeezed direction and the frequency of the information entropy squeezing
can be controlled by choosing the phase of the atom dipole and the relative competing
strength of atom-field, respectively.
We find that, under the same condition, no atomic variance squeezing is predicted from the
HUR while optimal entropy squeezing is obtained from the EUR, so the quantum information
entropy is a remarkable precision measure for the atomic squeezing
in the considered system. 相似文献