Quantum speed meter in laser gravitational antennas

A method of enhancing the sensitivity of laser gravitational antennas based on tracking of the velocity of the antenna reflectors instead of conventional tracking of their displacement is considered. This method allows one to overcome the standard quantum detection limit for a weak force. An optical scheme of a gravitational wave detector on the basis of a speed meter is considered. The formulas for the limiting sensitivity of the given scheme taking optical losses into account are obtained. The possibility of realizing the considered measurement method in presently existing laser gravitational antennas is analyzed.     

Optimal interconnection of resonant gravitational antennas

A new scheme for interconnecting resonant gravitational antennas is considered. This algorithm is based on the theory of combined detection and estimation of a vectorial signal on a pseudo-gravitational impulse background. The used minimax approach takes into account the beats between gravitational and pseudo-gravitational signals.     

Recognition of gravitation impulses on a correlated non-Gaussian noise background

We consider the problem of gravitation-wave impulse recognition against the background of correlated noise produced by resonance gravitational antennas. A new algorithm for the joint processing of data recorded by spatially separated gravitational detectors is obtained. The algorithm is an alternative to the coincidence scheme, which is traditionally used in gravitation-wave experiments. It is based on the principles, well known in statistical radiophysics, of joint detection and parameter estimation in quasi-deterministic signals.     

Thermal noises and noise compensation in high-reflection multilayer coating

Thermal fluctuations of different origin in the substrate and in the coating of optical mirrors produce phase noise in the reflected wave. This noise determines the ultimate stabilization capability of high-Q cavities used as a reference system. In particular this noise is significant in interferometric laser gravitational wave antennas. It is shown that simple alteration of a mirror multilayer coating may provide suppression of phase noise produced by thermorefractive, thermoelastic, photothermal and thermoradiation induced fluctuations in the coating.     

Investigation of optical inhomogeneities of multilayered reflecting coatings with high spatial resolution

An original method for the diagnostics of reflecting coatings is proposed. This method is applied to the investigation of multilayered mirrors used in laser gravitational antennas. The possible influence of the detected defects on the sensitivity of antennas is discussed.     

Thin walled Nb tubes for suspending test masses in interferometric gravitational wave detectors

In a previous Letter, we have shown that the use of orthogonal ribbons could provide a better mirror suspension technique in interferometric gravitational wave antennas. One of the key improvements presented by the orthogonal ribbon is the reduction in the number of violin string modes in the direction of the laser. We have considered more elaborate geometries in recent simulations and obtained a suspension that provides further reduction in the number of violin string modes in the direction of the laser, as well as in the direction orthogonal to the laser. This thin walled niobium tube suspension exhibits a reduction in the number of violin modes to 5 in each direction up to a frequency of 5 kHz. Furthermore, the violin mode thermal noise peaks can be reduced in amplitude by 30 dB.     

The possibility of using cryofiber interferometer as detector of gravitational waves

The history of the question on the possibility of detecting gravitational waves, whose existence is predicted by the General Relativity Theory, is briefly presented. The schemes of cryofiber interferometer, which we propose to use as detector of gravitational waves with amplitude |δg _ij | = 10^?20, are described. We also consider other versions of the use of cryofiber interferometer in both applied and fundamental context, including laboratory experiments in which according to the estimates dark energy density variations can be detected. We describe briefly the optical scheme of a compact interferometric detector of vibrations of a mirror fixed at the end of a massive gravitational antenna; the compactness admits construction of a cryogenic version with cooling of all the elements of such a recording system.     

300mm平面标准镜装卡结构的关键参数

为了实现大口径平面标准镜的高精结构装卡,对其在重力作用下的面形变化进行了研究。首先,对结构胶的有限元建模进行了理论分析,建立了大口径平面标准镜胶结装卡结构有限元模型。然后,分析了不同胶点数量及分布、不同胶接面积以及不同镜框支撑方式等关键结构参数对参考面面形的影响。最后,设计了大口径平面标准镜胶结及支撑的结构。结果表明,采用胶点直径为5 mm,12×3胶点分布形式胶结时,参考面面形的PV值为24.06 nm,RMS值为6.78 nm,满足了大口径平面标准镜面形精度的要求。     

Balanced heterodyne signal extraction in a postmodulated Sagnac interferometer at low frequency

We describe a balanced-heterodyne postmodulated Sagnac interferometer signal extraction method that is suitable for gravitational wave detection. The method is simple to implement by placement of a polarization-selective modulator after the beam splitter in the dark port of the interferometer. The postmodulated Sagnac interferometer retains its common path advantage and exhibits insensitivity to laser frequency noise below, at, and above the heterodyne frequency. Balanced detection reduces sensitivity to laser amplitude noise. In this scheme mirror displacement signals were rf demodulated and observed from 0.2 to 10kHz.     

Radiation field of spherical mirror antennas

The unique features of radiation pattern formation in spherical mirror antennas are determined. It is shown that in antennas of this type there is a possibility of doubling directivity by placement of the feed at the paraxial focus. Equations are developed for calculation of the optimum feed placement, effective aperture radius, directional pattern width, and side lobe level. It is shown that side-lobe radiation from a spherical mirror antenna is formed by geometric optical reflection of the feed field on the peripheral portion of the mirror.Sevastopol Instrument Engineering Institute. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 34, No. 2, pp. 173–176, February, 1991.     

The gravitational wave symphony of the Universe

The new millennium will see the upcoming of several ground-based interferometric gravitational wave antennas. Within the next decade a space-based antenna may also begin to observe the distant Universe. These gravitational wave detectors will together operate as a network taking data continuously for several years, watching the transient and continuous phenomena occurring in the deep cores of astronomical objects and dense environs of the early Universe where gravity was extremely strong and highly nonlinear. The network will listen to the waves from rapidly spinning non-axisymmetric neutron stars, normal modes of black holes, binary black hole inspiral and merger, phase transitions in the early Universe, quantum fluctuations resulting in a characteristic background in the early Universe. The gravitational wave antennas will open a new window to observe the dark Universe unreachable via other channels of astronomical observations.     

Earth-based gravitational wave detection from pulsars

The main features of continuous gravitational radiation bathing the Earth has been evaluated for a set of 558 pulsars. In particular, the maximum gravitational wave background and the maximum gravitational wave emission have been evaluated for each source and compared with the projected sensitivities of the planned Earth based very long baseline interferometric antennas for gravitational wave detection, like VIRGO and LIGO. This study shows that such detectors have a good chance of detecting gravitational waves emitted from this class of astrophysical sources.     

Gravitational Perturbations in Einstein Aether Black Hole Spacetime

We study the gravitational perturbations in Einstein aether black hole spacetime and find that the quasinormal modes(QNMs) of the first kind of aether black hole are similar to that of a Lorentz violation(LV) model,the quantum electrodynamics(QED) extension limit of standard model extension. These similarities between completely different backgrounds may imply that LV in the gravity sector and LV in the matter sector have some connections: damping QNMs more rapidly and prolonging its oscillation period. Compared to the Schwarzschild case, the first kind of black holes have larger damping rates and the second ones have lower damping rates, and they all have smaller real oscillation frequency. These differences could be detected by the new generation of gravitational antennas.     

Suppression of narrow-band non-Gaussian noise at the output of resonant gravitational antennas

The amplitude-frequency suppression of correlated non-Gaussian noise at the output of the line channel of resonant gravitational antennas is considered in the case of coherent information processing in the fast filtering mode.     

Quantum non-demolition observables for a weber-type gravitational wave antenna coupled to a resonant transducer

We present a general proof of the QND nature of the complex amplitudes for two coupled harmonic oscillators. The possibilities of the QND schemes for the detection of gravitational waves with a Weber-type antenna coupled to a resonant transducer are discussed, as well as their importance for the design of the next generation of gravitational wave antennas.     

Upper limit on the flux of gravitational wave bursts

Summary The data obtained with three highly sensitive gravitational wave antennas have been used to establish an improved observational upper limit on the flux of impulsive gravitational waves. Preliminary results under the assumption of a source located in the center of the Galaxy are also reported. To speed up publication, the proofs were not sent to the authors and were superised by the Scientific Committee.     

Background Noise Reduction in Gravitational Wave Detectors Through Use of an Amplitude Ratio Filter

Bursts of gravitational waves may be detected by searching for coincidental excitations between multiple, widely-spaced antennas. However, accidental coincidences due to random, local sources of excitation may mask true events due to gravitational waves. In this paper, we demonstrate experimentally that the use of an amplitude ratio filter can reduce the rate of accidental coincidences between two resonant-bar gravitational wave detectors, improving the statistical significance of zero time delay coincidences.     

Electromagnetic detector for gravitational waves

We analyze the mode of operation of a two-level parametric electromagnetic detector for gravitational waves which is tunable and potentially more sensitive than the mechanical antennas currently considered.     

Model for gravitational interaction between dark matter and baryons

We propose a phenomenological model where the gravitational interaction between dark matter and baryons is suppressed on small, subgalactic scales. We describe the gravitational force by adding a Yukawa contribution to the standard Newtonian potential and show that this interaction scheme is effectively suggested by the available observations of the inner rotation curves of small mass galaxies. Besides helping in interpreting the cuspy profile of dark matter halos observed in N-body simulations, this potential regulates the quantity of baryons within halos of different masses.     

冲击脉冲辐射天线辐射场计算及应用

根据由张量法得到的任意线天线电场计算公式,利用镜像法推导,得到冲击脉冲辐射天线辐射电场的时域解析表达式。应用该表达式计算冲击脉冲辐射天线应用于辐射波电磁脉冲模拟器的时域辐射场,并与数值计算进行比较,结果表明:解析计算得到的辐射场波形与数值计算结果吻合较好,因此,利用解析表达式可以方便地观察天线结构参数对天线辐射场波形的影响,从而选取合适的参数以产生符合标准要求的天线场波形。