共查询到20条相似文献,搜索用时 15 毫秒
1.
In a particular model of the pomeron, its gluon and quark distributions are subject to anti-shadowing, as described by a modified GLR equation recently derived. Inclusion of antishadowing cures the problem of momentum nonconservation previously existing in the GLR equation. A possible outcome of a measurement of the pomeron structure function at HERA is shown in case of DGLAP, GLR and modified GLR parton dynamics. 相似文献
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Bushev P Rotter D Wilson A Dubin F Becher C Eschner J Blatt R Steixner V Rabl P Zoller P 《Physical review letters》2006,96(4):043003
Based on a real-time measurement of the motion of a single ion in a Paul trap, we demonstrate its electromechanical cooling below the Doppler limit by homodyne feedback control (cold damping). The feedback cooling results are well described by a model based on a quantum mechanical master equation. 相似文献
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A light beam with an ideal wavefront that is transmitted or reflected from an object is modified by different characteristics of the object such as shape, refractive index, density, or temperature. Wavefront sensing therefore yields valuable information about the system or the changes happening to the system. A new method for wavefront sensing using a random amplitude mask and a phase retrieval method based on the Rayleigh-Sommerfeld wave propagation equation is described. The proposed method has many potential applications ranging from phase contrast imaging and measurement of lens aberration to shape measurement of three-dimensional objects. 相似文献
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V. P. Belavkin 《Letters in Mathematical Physics》1990,20(2):85-89
A stochastic model of the continuous counting nondemolition measurement of photons emitted by an excited atom in a quantum electromagnetic field is given. It is proved that the posterior dynamics of such an atom is described by a new nonlinear stochastic wave equation showing the relaxation of the atom to its ground state due to the photon emission. 相似文献
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Interferometers with long optical paths in air usually require knowledge and control of air dispersion. In addition, the measurements at several wavelengths and the dispersion properties of air allow errors caused by air turbulence to be compensated for. An innovative technique for air-dispersion measurement is described for long-baseline ground-based stellar interferometers. The technique combines second-harmonic interferometry and heterodyne detection to permit high-resolution measurement even for low optical powers. Experimental results show measurements of air dispersion in good agreement with the values predicted from the Edlén equation. 相似文献
7.
A quantum system \({\mathcal S}\) undergoing continuous time measurement is usually described by a jump-diffusion stochastic differential equation. Such an equation is called a quantum filtering equation (or quantum stochastic master equation) and its solution is called a quantum filter (or quantum trajectory). This solution describes the evolution of the state of \({\mathcal S}\) . In the context of quantum non demolition measurement, we investigate the large time behavior of this solution. It is rigorously shown that, for large time, this solution behaves as if a direct Von Neumann measurement has been performed at time 0. In particular the solution converges to a random pure state which can be directly linked to the wave packet reduction postulate. Using the theory of Girsanov transformation, we obtain the explicit rate of convergence towards this random state. The problem of state estimation (used in experiment) is also investigated. 相似文献
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DSM-LPDF两相湍流模型及旋流两相流动的模拟 总被引:2,自引:0,他引:2
本文由流体-颗粒速度的拉氏联合概率密度函数(PDF)输运方程出发,用Simonin建议的Langevin模型封闭颗粒所遇到流体瞬时速度的条件期望项,并用Monte Carlo方法直接求解 PDF输运方程,将其和求解流体雷诺应力方程模型的有限差分方法结合,建立了雷诺应力-拉氏PDF(DSM-LPDF,简称DL)两相湍流模型.用此模型模拟了旋流数为0.47的突扩旋流气粒两相流动,并与文献中PDPA实验和用类似于单相流动湍流模型封闭方法的时平均统一二阶矩(USM)模型的预报进行了对比. 相似文献
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V. P. Belavkin 《Communications in Mathematical Physics》1992,146(3):611-635
A quantum stochastic model for the Markovian dynamics of an open system under the nondemolition unsharp observation which is continuous in time, is given. A stochastic equation for the posterior evolution of a quantum continuously observed system is derived and the spontaneous collapse (stochastically continuous reduction of the wave packet) is described. The quantum Langevin evolution equation is solved for the case of a quasi-free Hamiltonian in the initial CCR algebra with a linear output channel, and the posterior dynamics corresponding to an initial Gaussian state is found. It is shown for an example of the posterior dynamics of a quantum oscillator that any mixed state under a complete nondemolition measurement collapses exponentially to a pure Gaussian one. 相似文献
12.
A. A. Veldhorst L. Bøhling J. C. Dyre T. B. Schrøder 《The European Physical Journal B - Condensed Matter and Complex Systems》2012,85(1):21
Zeroth-order complex dispersion equation of a cylindrical metallic nanowire has been
solved analytically to get dispersion relations of surface plasmon-polaritons (SPPs) by
approximate methods. The back bending of the dispersion relation can be well described by
the analytical solutions, confirming that the back bending is originated from the metal
Ohmic loss. Basing on the analytical solutions, the back bending point of the dispersion
relation used for the measurement of the metallic Ohmic loss has also been suggested. 相似文献
13.
A novel algorithm based on a phase modulation and demodulation technique for multiple self-mixing interferometry was proposed in this paper. This algorithm can measure nanoscale vibration in real time and enhance the measurement resolution of a multiple self-mixing interferometer twofold compared with that of a self-mixing interferometer. In this paper, the principles of the method were described in detail, and a phase equation for multiple self-mixing interferometry was derived. Experiments were confirmed by conducting a series of experiments with different amplitudes, different signal-to-noise ratios, and different vibration waveforms. The experimental results showed that the algorithm can rapidly demodulate vibration in real time and indicated good agreement between theory and experiment. 相似文献
14.
We study a tunnel contact that acts as charge detector for a single-electron transistor(SET) focusing on correlations between the detector current and the current through theSET. This system can be described fully by a Markovian master equation for the SET, whileelectron tunneling in the charge monitor represents a process with a stochastic rate,which can be solved exactly. It turns out that current monitoring is possible as long asthe detector current correlates with the currents through either SET barrier. By contrast,correlations with the effective current according to the Ramo-Shockley theorem are notessential. Moreover, we propose the measurement of the SET barrier capacitances. 相似文献
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The flow curve of wormlike micelles usually exhibits a stress plateau sigma* separating high and low viscosity branches, leading to shear-banded flows. We study the flow of semidilute wormlike micellar systems in a confined geometry: a straight microchannel. We characterize their local rheology thanks to particle image velocimetry. We show that flow curves cannot be described by a simple constitutive equation linking the local shear stress to the local shear rate. We demonstrate the existence of nonlocal effects in the flow of wormlike micellar systems and make use of a theoretical framework allowing the measurement of correlation lengths. 相似文献
17.
We report on electron emission from tungsten tips with the help of 800 nm-8 fs laser pulses from a Ti:sapphire laser oscillator. We have measured autocorrelation traces of the exciting laser pulse in the photoelectron current, which allows a measurement of the non-linearity as a function of DC voltage applied to the tip. These data are well described by a numerical integration of the one-dimensional Schrödinger equation. The simulation shows us that electron emission resolves the electric field structure of the driving laser pulse, a regime which is currently an extremely fruitful area of research with atoms in the gas phase. For an 8 fs laser pulse with the correct carrier-envelope phase setting the emission duration is as short as 800 nm. 相似文献
18.
Yu. M. Maksimov 《Russian Physics Journal》1976,19(5):595-598
The general nature of the dynamics that can be described by an equation for the density matrix of nonrelativistic quantum systems previously proposed by us [1] is studied. It is shown that it leads to an experimentally observed constraint on the states of the microscopic and quasi-macroscopic systems by states that can be described by more or less localized wave packets in phase space and replaces the ordinary spreading of these packets by statistically deterministic transitions between corresponding states. This makes possible a purely dynamic solution of the problem of the classical object and of the problem of measurement in quantum mechanics.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 63–67, May, 1976.I wish to express my deep appreciation to Prof. V. G. Bagrov for his interest in the study and for criticism. 相似文献
19.
P. Borys Z. J. Grzywna J. Łuczka 《The European Physical Journal B - Condensed Matter and Complex Systems》2011,83(2):223-233
We consider a deterministic process described by a discrete one-dimensional chaotic map and study its diffusive-like properties. Starting with the corresponding Frobenius-Perron equation we derive an approximate evolution equation for the probability distribution which is a partial differential equation of a hyperbolic type. Consequently, the process is correlated, non-Markovian, non-Gaussian and the information propagates with a finite velocity. This is in clear contrast to conventional diffusion processes described by a standard parabolic diffusion equation with an infinite velocity of information propagation. Our approach allows for a more complete characterisation of diffusion dynamics of deterministic systems. 相似文献
20.
L. Wan Y. M. Huang C. K. Dong H. J. Luo 《The European Physical Journal B - Condensed Matter and Complex Systems》2012,85(1):17
Zeroth-order complex dispersion equation of a cylindrical metallic nanowire has beensolved analytically to get dispersion relations of surface plasmon-polaritons (SPPs) byapproximate methods. The back bending of the dispersion relation can be well described bythe analytical solutions, confirming that the back bending is originated from the metalOhmic loss. Basing on the analytical solutions, the back bending point of the dispersionrelation used for the measurement of the metallic Ohmic loss has also been suggested. 相似文献