Frequency dependence of the amplitude of domain-wall oscillations in an acoustic wave field

The velocity of oscillatory motion of domain walls is investigated as a function of the parameters of a magnetic material and an external acoustic field. The dependence of the amplitude of domain-wall oscillations on the frequency of an external acoustic wave is determined. It is found that this dependence exhibits a resonant behavior.     

Controlled splitting of an atomic wave packet

We propose a simple scheme capable of adiabatically splitting an atomic wave packet using two independent translating traps. Implemented with optical dipole traps, our scheme allows a high degree of flexibility for atom interferometry arrangements and highlights its potential as an efficient and high fidelity atom optical beam splitter.     

Motion of an electronic wave packet in an electromagnetic field

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)     

Second-order corrections to neutrino two-flavor oscillation parameters in the wave packet approach

We report about an analytic study involving the intermediate wave packet formalism for quantifying the physically relevant information which appears in the neutrino two-flavor conversion formula and helping us to obtain more precise limits and ranges for neutrino flavor oscillation. By following the sequence of analytic approximations where we assume a strictly peaked momentum distribution and consider the second-order corrections in a power series expansion of the energy, we point out a residual time-dependent phase which, coupled with the spreading/slippage effects, can subtly modify the neutrino-oscillation parameters and limits. Such second-order effects are usually ignored in the relativistic wave packet treatment, but they present an evident dependence on the propagation regime so that some small modifications to the oscillation pattern, even in the ultra-relativistic limit, can be quantified. These modifications are implemented in the confrontation with the neutrino-oscillation parameter range (mass-squared difference Δm² and the mixing angle θ) where we assume the same wave packet parameters previously noticed in the literature in a kind of toy model for some reactor experiments. Generically speaking, our analysis parallels the recent experimental purposes which are concerned with higher precision parameter measurements. To summarize, we show that the effectiveness of a more accurate determination of Δm² and θ depends on the wave packet width a and on the averaged propagating energy flux Ē which still correspond to open variables for some classes of experiments. PACS 02.30.Mv; 03.65.Pm; 14.60.Pq     

Frequency and amplitude perturbation analysis of electroglottograph during sustained phonation

Electroglottography (EGG) was used to monitor vocal fold vibration patterns in normal subjects and patients with various laryngeal disorders. In order to evaluate the regularity of vocal fold vibration, frequency and amplitude perturbation of EGG waves during sustained phonation were measured with a laboratory computer. The data were compared to the degree of hoarseness evaluated by auditory perception and by sound spectrographic analysis. Frequency and amplitude perturbation measures showed some overlap between normal and pathological groups. However, there was a close relation between perturbation analysis of EGG waves and degree of hoarseness (Spearman's rank correlation coefficient rs = 0.73, p less than 0.0005). Amplitude perturbation was found to be a more sensitive measure of the irregularity of vocal fold vibration than frequency perturbation.     

Observing the phase space trajectory of an entangled matter wave packet

We observe the phase space trajectory of an entangled wave packet of a trapped ion with high precision. The application of a spin-dependent light force on a superposition of spin states allows for coherent splitting of the matter wave packet such that two distinct components in phase space emerge. We observe such motion with a precision of better than 9% of the wave packet extension in both momentum and position, corresponding to a 0.8 nm position resolution. We accurately study the effect of the initial ion temperature on the quantum entanglement dynamics. Furthermore, we map out the phonon distributions throughout the action of the displacement force. Our investigation shows corrections to simplified models of the system evolution. The precise knowledge of these dynamics may improve quantum gates for ion crystals and lead to entangled matter wave states with large displacements.     

Observation of wave packet dichotomy and adiabatic stabilization in an optical waveguide

We report on the first experimental observation of wave packet dichotomy and adiabatic stabilization of light in a periodically bent optical waveguide in analogy with similar behavior of atoms in high-frequency strong laser fields.     

Phase and amplitude collective modes of an incommensurate spin density wave

We examine the collective modes of an incommensurate quasi-one-dimensional spin density wave associated with oscillations in the phase and amplitude of its complex order parameter. Using a linear response formalism that ensures gauge- and translational-invariance the effects of the Coulomb repulsion in the particle-particle channel are shown to simply renormalise the velocity of the massless phase mode to a value higher than the Fermi velocity. Analytic results for the frequency and damping of the massive amplitude mode are presented. These two longitudinal collective modes remain decoupled for arbitrary wavevector q.     

Collapse of the wave packet without mixture

An explicit model of the quantum measurement process with determinstic dissipative dynamics is presented. The usual results of quantum mechanics are recovered, in complete compatibility with the realistic interpretation. The model exhibits the famous reduction of the wave packet and the occurrence of probability is explained as being due to a random correlation variable whose value is fixed at the very beginning of each of the individual processes. The way that the experimentalist observes the result has no effect on the final state of the system and, consequently, paradoxes like Schrödinger's cat or Wigner's friend are avoided.Partially supported by the Swiss National Science Foundation.     

Hydrodynamic flow patterns and synchronization of beating cilia

We calculate the hydrodynamic flow field generated far from a cilium which is attached to a surface and beats periodically. In the case of two beating cilia, hydrodynamic interactions can lead to synchronization of the cilia, which are nonlinear oscillators. We present a state diagram where synchronized states occur as a function of the distance of cilia and the relative orientation of their beat. Synchronized states occur with different relative phases. In addition, asynchronous solutions exist. Our work could be relevant for the synchronized motion of cilia generating hydrodynamic flows on the surface of cells.     

Time development of a wave packet and the time delay

A one-dimensional scattering problem off a δ-shaped potential is solved analytically and the time development of a wave packet is derived from the time-dependent Schrödinger equation. The exact and explicit expression of the scattered wave packet supplies us with interesting information about the “time delay” by potential scattering in the asymptotic region. It is demonstrated that a wave packet scattered by a spin-flipping potential can give us quite a different value for the delay times from that obtained without spin-degrees of freedom.     

Control the revisit time of the electron wave packet

Ionization of molecules by strong laser fields launches an electron wave packet. This electron wave packet, which can be driven back by the field to recollide with the parent ion, has been widely explored to probe the ultrafast nuclear dynamics. We numerically demonstrate the precise control of the temporal characteristic of the recolliding electron wave packet (REWP) by orthogonally polarized two-color fields. Through changing the relative phase of the two fields, the revisit time of REWP can be manipulated with a resolution of less than 200 attos, thus significantly improving the resolution of the well known molecular clock. This provides an efficient method for real-time observation of the ultrafast molecular dynamics with attosecond resolution.     

Reduction of the wave function: an operational approach

Possible experimental demonstration of the reduction hypothesis is discussed. It is argued that the two-time distribution function w(t₁, t₂), measurable in the time-of-flight experiments, can not be calculated without the reduction postulate. The calculation of w(t₁, t₂), using the Wigner rule and a model of the particle's detection process, is presented.     

On the mass of a wave packet in plasma

The relativistic mass density which is transported by a quasi-monochromatic transverse wave packet is derived. The wave packet is assumed to propagate in isotropic cold collisionless plasma. The co-ordinate frame moving with the group velocity appears as the rest frame for both the mass density and the total mass of the wave packet. The equivalence of the energy-mass relation and the dispersion equation is demonstrated.     

IBr分子含时波包的理论探究

本文主要对IBr分子的飞秒含时光电子能谱进行了模拟计算.运用含时量子波包方法,对不同延迟时间的光电子能谱进行模拟计算与理论分析.应用波包和光诱导势理论,对光电子能谱共同的两峰系特征及多峰现象给予合理解释.光电子能谱的峰值随延迟时间的增加而递减现象,是由于波包在势能面上因分子解离发散,使整个波包在势能曲线上的振荡递减造成的.研究表明：波包的传播是一个能量减弱的过程;跃迁过程中不同电离通道之间的竞争,也对能谱存在一定的影响.