Modulation of the vacuum field in the beam splitter and mirror system

We present modulation of the vacuum field with a single mirror placed close to an unused port of a beam splitter. The electromagnetic field modes of the vacuum fluctuation near the mirror are modified with respect to those in free space, with their amplitudes having a sinusoidal spatial dependence upon the distance from the mirror. If we combine this spatially amplitude-modulated vacuum field mode and a coherent local oscillator with a beam splitter, we may obtain squeezed states of light in a homodyne detection scheme. We show that the amplitude fluctuation of the combined light can be reduced by a factor of below that of the coherent light and the fluctuations of the intensity difference of the two beams can be also reduced.     

The IWOP Technique and Wigner-Function Approach to Quantum Effect of Mesoscopic Biological Cell

Using the IWOP technique, Wigner function theory and TFD theory, the quantization of a mesoscopic biological cell equivalent circuit is proposed, The quantum fluctuations of the mesoscopic biological cell are researched in thermal vacuum state and vacuum state. It is shown that the IWOP technique, Wigner function theory and Umezawa-Takahashi’s TFD theory play the key role in quantizing a mesoscopic biological cell at finite temperature and the fluctuations and uncertainty increase with increasing temperature and decrease with prolonged time.     

Interferometric study of phase fluctuations of laser radiation

An interferometric method is proposed for studying the phase fluctuations of laser radiation during propagation in media with random inhomogeneities. It differs from other methods in that the beam is split into two by the first mirror of a Jamin interferometer before the beam enters the medium. The visibility of the intereference pattern is related functionally to the correlation coefficient of the amplitude fluctuations and the structure function of the phase fluctuations. Results found in an experimental study of phase fluctuations by this method are reported.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii Fizika, No. 11, pp. 103–108, November, 1970.     

The fluctuation–dissipation theorem

A system in equilibrium will in general exhibit microscopic fluctuations about the equilibrium state. The fluctuation–dissipation theorem relates the spectrum of these fluctuations to a solution of the macroscopic equation describing the approach to equilibrium from a non-equilibrium state. The aim here is to show exactly what the theorem is and how it is to be used. An account of the quantum version of the theorem is given in three parts, depending on the solution of the macroscopic equation used to express the fluctuations: the relaxation function, the response function or the Green function for continuous systems. Each part is illustrated with an example: charge fluctuations in an RLC circuit for the first two and electric field fluctuations in vacuum for the last.     

Independent photon deletions from quantized boson fields: The quantum analog of the Burgess variance theorem

It is demonstrated that if two boson fields are related by a process of independent random photon deletion, their moment-generating functions are related by an equation identical to that derived using classical arguments. A quantum analog of the Burgess variance theorem is recovered. The results confirm that the super- or sub-poissonian nature of a light beam is conserved, under the influence of independent Bernoulli deletions and/or additive independent Poisson noise. The identity results from the correspondence between classical and normally ordered correlation functions, for which vacuum fluctuations play no role.     

Spacelike Fluctuations of the Stress Tensor for de Sitter Vacuum

The two-point function characterizing the stresstensor fluctuations of a massless, minimally coupledfield for an invariant vacuum state in de Sitterspacetime is discussed. This two-point function is explicitly computed for spacelike-separatedpoints which are geodesically connected. We show thatthese fluctuations are as important as the expectationvalue of the stress tensor itself. These quantum field fluctuations will induce fluctuations inthe geometry of de Sitter spacetime. This paper is afirst step toward the computation of such metricfluctuations, which may be of interest for large-scale structure formation in cosmology. The relevanceof our results in this context is brieflydiscussed.     

Quantum fluctuations of vacuum stress tensors and spacetime curvatures

We analyze the quantum fluctuations of vacuum stress tensors and spacetime curvatures, using the framework of linear response theory which connects these fluctuations to dissipation mechanisms arising when stress tensors and spacetime metric are coupled. Vacuum fluctuations of spacetime curvatures are shown to be a sum of two contributions at lowest orders; the first one corresponds to vacuum gravitational waves and is restricted to light-like wavevectors and vanishing Einstein curvature, while the second one arises from gravity of vacuum stress tensors. From these fluctuations, we deduce noise spectra for geodesic deviations registered by probe fields which determine ultimate limits in length or time measurements. In particular, a relation between noise spectra characterizing spacetime fluctuations and the number of massless neutrino fields is obtained.     

Relativistic Quantum Field Inertia and Vacuum Field Noise Spectra

The equivalence statements for quantum scalar field vacuum states that havebeen used for the thermal-like Hawking effect and Unruh effect are surveyed.An important ingredient in this framework is the concept of a vacuum field noisespectrum, by which one can obtain information about the curvature invariants ofclassical worldlines (relativistic classical trajectories). It is argued, in the spiritof the free-fall-type universality, that the preferred quantum field vacua withrespect to accelerated worldlines should be chosen from the class of all thosepossessing stationary spectra for their quantum fluctuations. For scalar quantumfield vacua there are six stationary cases, as shown by Letaw some time ago,and reviewed here. However, nonstationary vacuum noises can be treated by afew mathematical methods that are mentioned as well. Since the informationabout the kinematical curvature invariants of the worldlines is of radiometricorigin, suggestions are given on the more useful application of such an academicformalism to radiation and beam radiometric standards for high-energyaccelerators and in astrophysics. We conclude with a look at related axiomaticquantum field topics and some other recent work.     

用于太赫兹光源的准等时性储存环的设计

介绍了一种获得准等时性储存环的方案,即调节Lattice参数,在色散段引入负色散函数从而降低线性滑相因子,获得短束团。根据此方案设计了用于相干太赫兹光源的准等时性储存环,结果给出了线形光学函数曲线以及粒子的动力学孔径,表明了通过调节四极铁参数可以达到降低束团长度获得准等时性储存环的目的。还设计了用于准等时性储存环弯铁处的真空室的3维模型,并对其类腔体部分的本征模进行了计算,得到特性阻抗与品质因数的比值在10-3量级以下,表明类腔体部分对束流的影响很小。     

Casimir Torque for a Perfectly Conducting Wedge: A Canonical Quantum Field Theoretical Approach

The torque density per unit height exerted on a perfectly conducting wedge due to the quantum vacuum fluctuations (the Casimir torque) is obtained by calculating the vacuum-to-vacuum propagator (Green function) of a canonical quantum field. An erratum to this article is available at .     

Space charge oscillation in electron cooling devices

Electron cooling is used for improving the parameters of ion beams. The cooling efficiency depends drastically on the space charge fluctuation intensity in the beam. The fluctuations present in the cooling region cause the stochastic heating of the ions, which adversely affects the cooling efficiency and may even annihilate the ion beam. The space charge fluctuation intensity as a function of various operating parameters of a cooler is studied experimentally. A mechanism of fluctuation generation is suggested, and the effect of fluctuations on the ion beam parameters is estimated.     

The effect of laser fluctuation statistics upon detection probability

The effects of laser beam irradiance fluctuations, such as speckle and scintillation, upon optical beam detection probability are examined in an entirely statistical context. The optical detector is assumed to possess a non-linear integrated log-normal response function, as is normally ascribed to the eye. Various statistical distribution functions purported to model these fluctuations accurately are examined from both numerical and analytical standpoints. The numerical results indicate that different models for fluctuation statistics predict detector threshold probabilities which differ from each other by more than 10%. Such variations may be significant in calculations relating to eye safety.     

Interference between spontaneous two-photon radiation from two macroscopic regions

Interference is observed between the spontaneous parametric radiation from two nonlinear crystals separated by a macroscopic air gap and excited in series by a common pump beam. The phase of the interference depends on the phase shifts at three frequencies. A simple quantum model agrees well with the experimental results and makes it possible to interpret the effect in terms of general vacuum fluctuations which give rise to the spontaneous emission of mutually coherent radiation from the two crystals. Pis’ma Zh. éksp. Teor. Fiz. 65, No. 1, 20–25 (10 January 1997)     

真空二极管辐射微波的机理分析

在研究真空开关的过程中,发现真空二极管能辐射出宽带微波.这种器件只由带触发装置的阴极和平板阳极组成,不存在金属波纹慢波结构,所以真空二极管的辐射机理与等离子体填充微波器件不同,不能直接套用等离子体填充微波器件的相关理论.本文描述了真空二极管产生辐射的物理过程,建立了真空二极管辐射的数学模型,通过求解波动方程得到产生辐射的色散关系,并绘制出了色散曲线.将理论分析得到的色散曲线与已经测得的微波辐射进行比较,两者能很好地符合.理论分析和实验结果表明,电子束和磁化等离子体的相互作用是真空二极管产生微波辐射的原因.     

Space-Time Curvature Induced by Quantum Vacuum Fluctuations as an Alternative to Dark Energy

It is shown that quantum vacuum fluctuations give rise to a curvature of space-time of the order appropriate to explain the observed accelerated expansion of the universe. The fact that the fluctuations produce curvature, even if the expectation of the vacuum energy vanishes, is a consequence of the non-linear character of the Einstein equation. A calculation is made, involving plausible hypotheses within quantized gravity, which establishes a relation between the two-point correlation of the vacuum fluctuations and the space-time curvature.     

THE CASIMIR FORCE BETWEEN POLARIZERS

The Casimir force between two parallel lincar polarizers oriented at an arbitrary angle is calculated. We compare two approaches, one by solving the field mode function in three-dimensional space with highly anisotropic dielectric slabs, the other by calculating the interaction between dipolcs induced by vacuum fluctuations in these slabs.     

Degree of polarization for single-photon beam in a turbulent atmosphere

The polarization fluctuations of single-photon beam propagation through the slant path turbulent atmosphere are studied. The Stokes operators and the degree of polarization of single-photon beam in a turbulent atmosphere are obtained. It is shown by analytical calculations, that the quantum degree of polarization of linearly polarization light is a decrease function of the atmospheric turbulence strength and the propagation distance for lower detection photon number.     

The chiral magnetic effect and chiral symmetry breaking in <Emphasis Type="Italic">SU</Emphasis>(3) quenched lattice gauge theory

We study some properties of the non-Abelian vacuum induced by strong external magnetic field. We perform calculations in the quenched SU(3) lattice gauge theory with tadpole-improved Lüscher-Weisz action and chirally invariant lattice Dirac operator. The following results are obtained: The chiral symmetry breaking is enhanced by the magnetic field. The chiral condensate depends on the strength of the applied field as a power function with exponent ν = 1.6 ± 0.2. There is a paramagnetic polarization of the vacuum. The corresponding susceptibility and other magnetic properties are calculated and compared with the theoretical estimations. There are nonzero local fluctuations of the chirality and electromagnetic current, which grow with the magnetic field strength. These fluctuations can be a manifestation of the Chiral Magnetic Effect.     

Moments of intensity distribution of super-Gauss beam in turbulent atmosphere

Moment of intensity distribution is one of the most important parameters in studying the propagation of a beam in turbulent atmosphere. With the help of Wigner transform and the expansion of mutual coherence function (MCF) of turbulence, a relation between the moment of intensity distribution and the moment of power spectrum of refractive index fluctuations is found. The study shows that the jth-order moment of beam intensity distribution is only affected by the moment of power spectrum of refractive index fluctuations which order is not larger than j. Meanwhile, the expressions for the moment of beam intensity distribution, in which order is not larger than the fourth order are given. As a special case, the moments of the super-Gaussian beam (SGB) in turbulence are studied. The evolution of the kurtosis parameters of SGB under different condition is investigated in detail.     

Instability of flatspace and the origin of conformal fluctuations

It is shown that conformal fluctuations in the metric can be initiated by the vacuum fluctuations of a scalar field with mass greater than the Planck mass. Flatspace is unstable against such fluctuations.