Adiabatic spectra during slowly evolving

In general, for single field, the scale invariant spectrum of curvature perturbation can be given by either its constant mode or its increasing mode. We show that during slowly expanding or contracting, the spectrum of curvature perturbation given by its increasing mode can be scale invariant. The perturbation mode can be naturally extended out of horizon, and the amplitude of perturbation is consistent with the observations. We briefly discuss the implement of this scenario.     

Classicality,the Ensemble Interpretation,and Decoherence: Resolving the Hyperion Dispute

We analyze seemingly contradictory claims in the literature about the role played by decoherence in ensuring classical behavior for the chaotically tumbling satellite Hyperion. We show that the controversy is resolved once the very different assumptions underlying these claims are recognized. In doing so, we emphasize the distinct notions of the problem of classicality in the ensemble interpretation of quantum mechanics and in decoherence-based approaches that are aimed at addressing the measurement problem.     

Self-synchronization of nonlinear oscillations in the presence of fluctuations

A statistical mechanical theory is presented for the self-organization of a macroscopic oscillation with the presence of external fluctuations in a system of Van der Pol oscillators coupled through dissipative interactions. Starting from Langevin equations for the Van der Pol oscillators, the static and dynamic characteristics are studied. The threshold condition is given by the relative size between the fluctuation and the interaction. The transitions between synchronous and asynchronous phases are well discussed by a Landau-type equation. The steady state value of the order parameter and the onset time are compared between the theory and the computer experiments and a good agreement is obtained.     

Berry phase of primordial scalar and tensor perturbations in single-field inflationary models

In the framework of the single-field slow-roll inflation, we derive the Hamiltonian of the linear primordial scalar and tensor perturbations in the form of time-dependent harmonic oscillator Hamiltonians. We find the invariant operators of the resulting Hamiltonians and use their eigenstates to calculate the adiabatic Berry phase for sub-horizon modes in terms of the Lewis–Riesenfeld phase. We conclude by discussing the discrepancy in the results of Pal et al. (2013) [21] for these Berry phases, which is resolved to yield agreement with our results.     

超导与自旋涨落

在常规超导体中,库珀对是由于电子与声子之间的相互作用而形成的. 在此过程中,人们可以只考虑电子的电荷性质与声子之间的关联. 然而在所谓的非常规超导体中,人们意识到一些其他类型的元激发也可能导致超导现象,而自旋涨落则可能是其中最重要的一种. 在大多数非常规超导体中,都可以发现自旋涨落的身影. 而在一些重要的体系中,包括铜基超导体、铁基超导体以及一些重费米子超导体体系等,可以确切地说,自旋涨落起到了关键的作用,尽管其相对应的超导机制仍然还不清楚. 文章简单介绍了自旋涨落与超导电性之间的关联.     

Critical fluctuations for quantum mean-field models

We propose a Ginzburg-Landau-type approximation for the local Gibbs states for quantum mean-field models that leads to the exact thermodynamics. Using this approach, we compute the spin fluctuations for some spin-1/2 models. At the critical temperature we find explicitly the distribution function showing abnormal fluctuations.On leave from the University of Torun, Poland.     

Intrinsic fluctuations and a phase transition in a class of large populations of interacting oscillators

A theory of intrinsic fluctuations is developed of a phase ordering parameter for large populations of weakly and uniformly coupled limit-cycle oscillators with distributed native frequencies. In particular it is shown that the intensity as well as the correlation time of fluctuations exhibit power-law divergence at the onset of mutual entrainment with critical exponents which depend on whether the coupling strength approaches the threshold from below or above. This peculiar feature is demonstrated by numerical simulations mainly through finite-size scaling analyses. In the course of exploring its origin, we encounter a new concept termed a correlation frequency which provides a natural interpretation of the finite-size scaling laws. A comment is given on a recent theory by Kuramoto and Nishikawa to clarify why it contradicts our results.     

Particle asymmetries in the early universe

The total lepton asymmetry l=∑_fl_f in our universe is only poorly constrained by theories and experiments. It might be orders of magnitudes larger than the observed baryon asymmetry b?O(10⁻¹⁰), |l|/b≤O(10⁹). We found that the dynamics of the cosmic QCD transition changes for large asymmetries. Predictions for asymmetries in a single flavour l_f allow even larger values. We find that asymmetries of l_f≤O(1) in single or two flavours may change the relic abundance of WIMPs. However, large lepton and large individual lepton flavour asymmetries influence significantly the dynamics of the early universe between the electroweak phase transition and the onset of neutrino oscillations.     

宇宙起源与阿里原初引力波探测

20世纪建立起的宇宙大爆炸模型取得了巨大的成功,但仍期待着新的革命性的突破。探知宇宙起源及其演化是新世纪对全世界科学家的新挑战,其重要性在近期公布的中国“十三五”规划纲要中得到了高度的肯定。现代宇宙学理论,暴胀以及非奇异宇宙模型如反弹等,预言了原初引力波的存在,但至今还没有被实验证实。不同于近期LIGO合作组探测到的黑洞引力波,原初引力波是宇宙诞生时期产生的,携带着丰富的宇宙学信息,是引力波探测的全新波段,是引力波探测的下一个突破方向。文章简述了中国的阿里原初引力波实验计划及相关的科学问题。     

Measurability of vacuum fluctuations and dark energy

Vacuum fluctuations of the electromagnetic field induce current fluctuations in resistively shunted Josephson junctions that are measurable in terms of a physically relevant power spectrum. In this paper we investigate under which conditions vacuum fluctuations can be gravitationally active, thus contributing to the dark energy density of the universe. Our central hypothesis is that vacuum fluctuations are gravitationally active if and only if they are measurable   in terms of a physical power spectrum in a suitable macroscopic or mesoscopic detector. This hypothesis is consistent with the observed dark energy density in the universe and offers a resolution of the cosmological constant problem. Using this hypothesis we show that the observable vacuum energy density _ρvac${\rho }_{\mathit{vac}}$ in the universe is related to the largest possible critical temperature _Tc$T_c$ of superconductors through _ρvac=σ·(_kTc)⁴/?³c³${\rho }_{\mathit{vac}}=\sigma ·({\mathit{kT}}_c{)}^4/{?}^3{c}^3$, where σ$\sigma$ is a small constant of the order 10^-3${10}^{-3}$. This relation can be regarded as an analog of the Stefan–Boltzmann law for dark energy. Our hypothesis is testable in Josephson junctions where we predict there should be a cutoff in the measured spectrum at 1.7 THz if the hypothesis is true.     

Altered state of primordial follicles in neonatal and early infantile rats due to maternal hypothyroidism: Light and electron microscopy approach

Thyroid hormones (TH) are one of the key factors for normal prenatal development in mammals. Previously, we showed that subclinical maternal hypothyroidism leads to premature atresia of ovarian follicles in female rat offspring in the pre-pubertal and pubertal periods. The influence of decreased concentration of TH on primordial follicles pool formation during neonatal and early infantile period of rat pups was not investigated previously. Maternal hypothyroidism during pregnancy has irreversible negative influence on primordial follicles pool formation and population of resting oocytes in female rat offspring. The study was done on neonatal and early infantile control (n-10) and hypothyroid (n-10) female rat pups derived from control (n-6) and propylthiouracil (PTU) treated pregnant dams (n-6), respectively. Ovaries of all pups were removed and processed for light and transmission electron microscopy (TEM). Number of nests, oogonia and oocytes per nest, primordial, primary, secondary and preantral follicles were determined. Screening for overall calcium presence in ovarian tissue was done using Alizarin red staining. Morphology and volume density of nucleus, mitochondria and smooth endoplasmic reticulum (sER) in the oocytes in primordial follicles was also assessed. Caspase-3 and terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL), both markers for apoptosis, and proliferating cell nuclear antigen (PCNA) for proliferation were determined in oocytes and granulosa cells in different type of follicles. In neonatal period, ovaries of hypothyroid pups had a decreased number of oogonia, oocytes and nests, an increased number of primordial follicles and a decreased number of primary and secondary follicles, while in early infantile period, increased number of primary, secondary and preantral follicles were found. Alizarin red staining was intense in hypothyroid neonatal rats that also had the highest content of dilated sER. Number of mitochondria with altered morphology in both groups of hypothyroid pups was increased. Apoptosis markers have not shown significant difference between groups but PCNA had an increased expression in the oocytes and granulosa cells in primordial follicles of hypothyroid rats. Light and electron microscopy analysis indicate that previously detected premature ovarian follicular atresia in pre-pubertal and pubertal hypothyroid rats is preceded with premature formation of primordial follicles followed by slight changes on sER and mitochondria in examined oocytes, and increased expression of PCNA.     

Spatial fluctuations in reaction-diffusion systems: A model for exponential growth

The spatial fluctuations in an exactly soluble model for the irreversible aggregation of clusters are treated. The model is characterized byrate constants K _ij =i+j for the clustering of ani- and aj-mer, anddiffusion constants D _j =D. It is assumed thatD1 (reaction-limited aggregation). Explicit expressions for the correlation functions at equal and at different times are calculated. The equal-time correlation functions show scaling behavior in the scaling limit. The correlation length remains finite ast, and the fluctuations becomelarge at large times (tt _D ) inany dimension. The crossover timet _D , at which the mean field theory (Smoluchowski's equation) breaks down, is given byt _D InD. These exact results imply that the upper critical dimension of this model isd _c= and, hence, that there isno unique upper critical dimension in models for the irreversible aggregation of clusters.     

Gaussian fluctuations for the magnetization of Lee-Yang ferromagnets at zero external field

We consider the fluctuations of the block spin magnetization normalized by the square root of the considered number of spins in a block for Lee-Yang ferromagnets. It is established that the fluctuations are Gaussian when ^d at zero external field whenever the susceptibility is finite (i.e., above the critical temperature) and converges to the second derivative of the pressure at zero field. The validity of this fluctuation-dissipation condition is known to hold for a large class of Lee-Yang models, including, for instance, classical Heisenberg ferromagnets.     

振幅和相位涨落对锁模脉冲列特性的影响

 用傅里叶变换的方法分析了锁模激光器中模式间的相位和振幅涨落对锁模脉冲列特性的影响。将锁模激光器中各模式的相位和振幅涨落作傅里叶展开，再通过增益谱抽样的傅里叶变化得到其时域行为。分析结果表明振幅系统涨落及随机涨落均不引起脉宽的明显变化，只引起脉冲间背景的加大，但相位涨落随机会使脉冲列强度产生波动。所用物理图像简明，结果对获得稳定的锁模脉冲列的实验研究有参考意义。     

振幅和相位涨落对锁模脉冲列特性的影响

用傅里叶变换的方法分析了锁模激光器中模式间的相位和振幅涨落对锁模脉冲列特性的影响。将锁模激光器中各模式的相位和振幅涨落作傅里叶展开,再通过增益谱抽样的傅里叶变化得到其时域行为。分析结果表明振幅系统涨落及随机涨落均不引起脉宽的明显变化,只引起脉冲间背景的加大,但相位涨落随机会使脉冲列强度产生波动。所用物理图像简明,结果对获得稳定的锁模脉冲列的实验研究有参考意义。     

Spectral fluctuations and zeta functions

We study theoretically and numerically the role of the fluctuations of eigenvalue spectra {it_n in a particular analytical continuation process applied to the (generalized) zeta functionZ(s)= _{n n} ^–s fors large and positive. A particularly interesting example is the spectrum of the Laplacian on a triangular domain which tessellates a compact surface of constant negative curvature (of genus two). We indeed find that the fluctuations restrict the abscissa of convergence, and also affect the rate of convergence. This then initiates a new approach to the exploration of spectral fluctuations through the convergence of analytical continuation processes.work done while at the Service de Physique Théorique, Saclay, and Institut de Physique Nucléaire, Orsay.     

Theoretical analysis and experimental scheme of QND measurement for intensity difference fluctuations

A feasible experimental scheme of QND measurement for intensity difference fluctuations is presented, in which a nondegenerate optical parametric amplifier is used as the nonlinear coupling device. Optimum behavior is obtained by appropriately choosing the operating parameters, which can provide design references for the measurement.