共查询到20条相似文献,搜索用时 31 毫秒
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We consider the model of a Bose condensate in the regime of velocity-selective coherent population trapping. As a result of interaction between particles, some fraction of atoms is outside the condensate, remaining in the coherent trapping state. These atoms are involved in brief events of intense interaction with external resonant electromagnetic fields. Intense induced and spontaneous transitions are accompanied by the exchange of momenta between atoms and radiation, which is manifested as migration of atoms in the velocity space. The rate of such migration is calculated. A nonlinear kinetic equation for the many-particle statistical operator for uncondensed atoms is derived under the assumption that correlations of atoms with different momenta are insignificant. The structure of its steady-state solution leads to certain conclusions about the above-mentioned migration pattern taking the Bose statistics into consideration. With allowance for statistical effects, we derive nonlinear integral equations for frequencies controlling the migration. The results of numerical solution of these equations are represented in the weak interatomic interaction approximation. 相似文献
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We investigate the nonlinear optical interaction through a periodic waveguide structure consisting of two alternating segments with different linear and nonlinear optical properties. A coupled equation system has been used to calculate the intensity of fundamental and second harmonic waves and the phase shift of the fundamental. The model has been experimentally tested with good results, but the effect of the phase shift has not been considered. Comparison with the quasi-phase match (QPM) technique has been presented. The novel features introduced by alternating segments with different linear and nonlinear optical properties have been discussed. The model shows a more flexible approach, which can be used in designing optical components based on coherent nonlinear interaction. Applications are straightforward for frequency doubler and all-optical switch. 相似文献
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An analysis, based on the variational approach, is carried out of the interaction between two fully coherent solitons as well as two partially coherent soliton stripes in a medium with logarithmic nonlinearity. For the coherent case, it is found that the interaction can be both attractive and repulsive depending on the relative phase. The different interaction scenarios involve a bound system where the distance between the solitons oscillates with various magnitude of the oscillation amplitude, including total coalescence, and another where the solitons separate asymptotically. The effect of partial coherence on the soliton interaction is also studied by analyzing the interaction between two partially coherent soliton stripes. It is found that the strength as well as the character (attractive/repulsive) of the interaction changes for decreasing coherence. Thus, the general interaction properties of solitons in logarithmic nonlinear media are qualitatively similar to those of solitons in nonlinear Kerr media. 相似文献
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q形变光场与级联型三能级原子相互作用中场的压缩效应 总被引:1,自引:0,他引:1
建立了q形变光场与级联型三能级原子相互作用的非线性理论,求得相互作用绘景中薛定谔方程的形式解,利用数值计算讨论了q形变对相互作用中场压缩效应的影响并与q-偶相干光场的情形做了对比分析。研究发现,q偏离1的程度越大,q形变对场压缩效应的调控能力越强,反映出q形变的非线性行为对量子相干性的干扰以及对量子特性的影响。当q→1时,恢复为普通线性理论。和q-偶相干光场的情形做的对比分析,反映出q-奇相干光场不仅不存在压缩效应,还会弱化压缩效应。这与q-偶相干光场和q-奇相干光场存在不同的量子效应的结论完全一致。 相似文献
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建立了q形变偶相干场与Ξ型三能级原子相互作用的非线性理论,求得了在相互作用表象中薛定谔方程的形式解及其在该形态下的期望值。数值计算结果表明,q形变对相互作用中场压缩效应有着很强的调制能力,这是q形变非线性行为对量子相干性干扰以及对量子特性影响的内在反映。当q→1时,恢复为普通的偶相干光场线性理论。 相似文献
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建立了q形变偶相干场与[I]型三能级原子相互作用的非线性理论,求得了在相互作用表象中薛定谔方程的形式解及其在该形态下的期望值.数值计算结果表明,q形变对相互作用中场压缩效应有着很强的调制能力,这是q形变非线性行为对量子相干性干扰以及对量子特性影响的内在反映.当q→1时,恢复为普通的偶相干光场线性理论. 相似文献
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In this paper, tunnelling dynamics of squeezed Bose-Einstein condensates (BEC's) in the presence of the nonlinear self-interaction of each species, the interspecies nonlinear interaction, and the Josephson-like tunnelling interaction is investigated by using the second quantization approach. The influence of BEC squeezing on macroscopic quantum self-trapping (MQST) and quantum coherent atomic tunnelling is analyzed in detail. It is shown that the MQST and coherent atomic tunnelling between two squeezed BEC's can be manipulated through changing squeezing amplitude and squeezing phase of BEC squeezed states. 相似文献
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P. A. Prudkovskii 《JETP Letters》2018,107(12):749-752
The effect of pump depletion on the spectrum of twin beams, which appear in the process of collinear parametric down-conversion in a nonlinear crystal with an aperiodic domain structure and have a high degree of simultaneity, has been described. A system of equations describing the interaction of pump with all modes of scattered light simultaneously has been derived. It has been shown that pump depletion results in a noticeable broadening of the spectrum of twin beams for a quadratic-hyperbolic law of variation of the reciprocal lattice vector of the domain structure. The effect of narrowing of the coherent peak in the sum-frequency generation signal from twin beams has been demonstrated. This effect increases as the pump is depleted. 相似文献
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The nonlinear generation of shear field and flow in whistler waves is considered. It is shown that a coherent parametric process leads to modulational instability of four waves whistler interaction. Growth rates for the flow/field are compared with published simulation results. 相似文献
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In this paper we propose a theoretical scheme to show the possibility of
generating various families of nonlinear (f-deformed) coherent states of the
radiation field in a micromaser. We show that these states can be provided
in a lossless micromaser cavity under the weak Jaynes-Cummings interaction
with intensity–dependent coupling of large number of individually injected
two-level atoms in a coherent superposition of the upper and lower states.
In particular, we show that the so-called nonlinear squeezed vacuum and
nonlinear squeezed first excited states, as well as the even and odd
nonlinear coherent states can be generated in a two-photon micromaser. 相似文献
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We investigate both experimentally and theoretically the interaction between a light beam and a photonic lattice optically induced with partially coherent light. We demonstrate a clear transition from two-dimensional discrete diffraction to discrete solitons in such a partially coherent lattice and show that the nonlinear interaction process is associated with a host of new phenomena including lattice dislocation, lattice deformation, and creation of structures akin to optical polarons. 相似文献
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Journal of Experimental and Theoretical Physics - The microscopic quantum theory of nonlinear interaction of strong coherent electromagnetic radiation with gapped bilayer graphene is used for... 相似文献
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The interference pattern generated by the merging interaction of two Bose-Einstein condensates reveals the coherent, quantum wave nature of matter. An asymptotic analysis of the nonlinear Schrödinger equation in the small dispersion (semiclassical) limit, experimental results, and three-dimensional numerical simulations show that this interference pattern can be interpreted as a modulated soliton train generated by the interaction of two rarefaction waves propagating through the vacuum. The soliton train is shown to emerge from a linear, trigonometric interference pattern and is found by use of the Whitham modulation theory for nonlinear waves. This dispersive hydrodynamic perspective offers a new viewpoint on the mechanism driving matter-wave interference. 相似文献
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卢道明 《原子与分子物理学报》2008,25(4):875-880
利用数值计算方法,研究了有限维Hilbert空间一种新的奇偶非线性相干态的反聚束效应.研究结果表明:各有限维Hilbert空间新的偶非线性相干态均不出现反聚束效应.但各有限维Hilbert空间新的奇非线性相干态均可出现反聚束效应. 相似文献