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1.
We study the effects of correlations between quantum and pump noises on fluctuationsof the laser intensity in a saturation laser model. An approximative Fokker--Planckequation and analytic expressions of the steady-state probability distributionfunction (SPD) of the laser system are derived. Based on the SPD, the normalizedmean, the normalized variance, and the normalized skewness of the steady-state laserintensity are calculated numerically. The results indicate that (i) the correlationstrength lambda of correlated noises always enhances the fluctuation of laserintensity; (ii) the correlation time tau of correlated noises strengthens thefluctuation of laser intensity for the below-threshold case but tau weakens itfor the above-threshold case. 相似文献
2.
虚实部关联噪声驱动的单模激光的动力学性质 总被引：2，自引：0，他引：2
基于虚、实部互关联的量子噪声及泵噪声驱动的单模激光模型的Fokker—Planck方程,运用平均弛豫近似方法研究了该激光模型的动力学性质。计算了光强关联函数以及相应的平均弛豫时间,讨论了量子噪声实虚部的互关联强度对光强关联函数以及弛豫时间的影响。结果表明,在阈值以上量子噪声实、虚部关联的存在总是使得光强涨落的弛豫变缓。 相似文献
3.
对具有色泵噪声和白量子噪声关联驱动的单模激光模型的稳态统计性质进行了研究。从交叉关联噪声驱动的修正郎之万方程(MLE)出发,利用近似福克-普郎克方程（AFPE),计算了稳态激光光强的平均值＜I＞、斜方差λ2(O)和偏斜率λ3(O),并分析了泵噪声的“颜色”对它们的影响。研究发现：1)泵噪声的自关联时间τ与量子和泵噪声的交叉关联强度λ对分布函数Pat的影响是完全相反的;2)τ基本上不影响平均光强＜I＞,但在阂值附近,λ会使＜I＞的涨落增加;3)λ和τ对λ2(O)和λ3(O)的影响是一样的。 相似文献
4.
This paper investigates a genotype selection model subjected to both a multiplicative coloured noise and an additive coloured noise with different correlation time τ1 and τ2 by means of the numerical technique. By directly simulating the Langevin Equation, the following results are obtained. （1） The multiplicative coloured noise dominates, however, the effect of the additive coloured noise is not neglected in the practical gene selection process. The selection rate μ decides that the selection is propitious to gene A haploid or gene B haploid. （2） The additive coloured noise intensity and the correlation time τ2 play opposite roles. It is noted that α and τ2 can not separate the single peak, while can make the peak disappear and ~-2 can make the peak be sharp. （3） The multiplicative coloured noise intensity D and the correlation time τ1 can induce phase transition, at the same time they play opposite roles and the reentrance phenomenon appears. In this case, it is easy to select one type haploid from the group with increasing D and decreasing τ1. 相似文献
5.
On the basis of the beaming model, we have derived a relation between the observed polarization (Pob) and Doppler-corrected optical magnitude (mcorr), log Pob=0.4(1-k) mcorr+C. We tested the correlation between Pob} and mcorr. The main results are as follows: (1) for both high and low states, there are strong correlations between Pob and mcorr for 29 RBLs with well-observed polarization and Doppler factor, where mcorr=mob+(3+α)logδ/0.4, and δ is the optical Doppler factor; (2) no correlation exists between Pob and the observed optical magnitude, mob, for the 29 RBLs in high state, but there is a close correlation for the 29 RBLs in low state; (3) however, there is an obvious anti-correlation between Pob and mcorr for 35 XBLs with good simultaneous observation data. Our results show that (i) a new difference in polarization is found between RBLs and XBLs; (ii) this difference in polarization between RBLs and XBLs seems really to be physical differences. 相似文献
7.
The nonequilibrium phase transition and the symmetryrevival induced by time delay in a bistable system are investigated.The stationary probability distribution function (SPDF) of thebistable system with time delay and correlated noises are calculatedby an analytical method and stochastic simulation respectively. Theanalytical and simulative results indicate that: (1) There is acertain value of λ (λ denotes the strength ofcorrelations between the multiplicative and additive noises) to makethe SPDF symmetric under some time delay; however, above or belowthe given value, the symmetry will be broken; (2) With themonotonic change of λ , the unimodal peak structure of SPDFbecomes bimodal at the beginning, then it becomes unimodal again; thismeans that there is a reentrance phenomenon in the process; (3)There is a critical value of delay time, which makes the lower peakof SPDF equal to the higher one under the critical condition. Thismeans that the symmetry revival phenomenon emerges. 相似文献
8.
利用随机模拟方法研究了惯性棘轮中非高斯噪声对负迁移率的影响. 分别模拟了绝对负迁移率(ANM), 非线性迁移率(NNM) 和负微分迁移率(NDM) 等三种反常输运现象. 计算结果表明: 1) 在不同的参数空间里, 非高斯噪声参数q 能够增强或者削弱ANM, 诱导NNM 和NDM; 2) 当q 较大时, 反常输运现象转化为正常输运; 3) 随着q 逐渐增大, 平均速度- 关联时间特性曲线朝着关联时间较小的方向移动并且其峰值逐渐减小.关键词：反常输运负迁移率非高斯噪声 相似文献
9.
We investigate the transport of a deterministic Brownian particle theoretically, which moves in simple onedimensional, symmetric periodic potentials under the influence of both a time periodic and a static biasing force. The physical system employed contains a friction coefficient that is speed-dependent. Within the tailored parameter regime, the absolute negative mobility, in which a particle can travel in the direction opposite to a constant applied force, is observed.This behavior is robust and can be maximized at two regimes upon variation of the characteristic factor of friction coefficient. Further analysis reveals that this uphill motion is subdiffusion in terms of localization(diffusion coefficient with the form D(t) ~t~(-1) at long times). We also have observed the non-trivially anomalous subdiffusion which is significantly deviated from the localization; whereas most of the downhill motion evolves chaotically, with the normal diffusion. 相似文献
10.
Intracellular calcium ion concentration oscillation in a cell subjected to external noise and irradiated by an electromagnetic field is considered. The effects of the intensity E0, the polar angle θ and the frequency omega of the external electric field on steady-state probability distribution and the mean Ca2+ concentration, respectively, are investigated by a numerical calculation method. The results indicate that (i) variation of ω cannot affect the intracellular calcium oscillation; (ii) the steady-state probability distribution presents a meaningful modification due to the variations of E0 and θ, while variation of θ does not affect the steady-state probability distribution under the condition of a small E0, and E0 cannot affect the steady-state probability distribution either when θ = π/2; (iii) the mean Ca2+ concentration increases as E0 increases when θ < π/2 and, as θ increases, it first increases and then decreases. However, it does not vary with E0 increasing when θ = π/2, but it increases with θ increasing when E0 is small. 相似文献