Li Fang-Yu

Resonant Interaction Between a Weak Gravitational Wave and a Microwave Beam in the Double Polarized States Through a Static Magnetic Field

We investigate the resonant interaction to the weak gravitational waves in a coupling electromagnetic system, which consists of a Gaussian beam with the double polarized transverse electric modes, a static magnetic field and the fractal membranes. We find that under the syncroresonance condition a high-frequency GW (HFGW) of h=10^-30,v_g=3GHz may produce the perturbative photon flux (PPF) of 2.15*10/s in a surface of 0.01m^2. The PPF can be pumped out from the background photon fluxes and one might obtain the amplified signal photon flux of 2.15*10^4s^-1 by cascade fractal membranes. It appears to be worthwhile to study this effect for the detection of the high-frequency relic GWs in quintessential inflationary models and the HFGWs expected by possible laboratory schemes.We investigate the resonant interaction of a weak gravitational wave with a microwave beam in a coupling electromagnetic system, which consists of a Gaussian beam with double polarized transverse electric modes, a static magnetic field and fractal membranes. We find that under the synchroresonance condition, a high-frequency gravitational wave in amplitude 10−30 and frequency 3 GHz may produce the perturbative photon flux of 2.15×10 s−1 in a surface of 10−2 m2. The perturbative photon flux can be pumped out from the background photon fluxes and one may obtain the amplified signal photon flux of 2.15×104 s−1 by cascade fractal membranes. It is worth studying this effect for the detection of high-frequency relic gravitational waves in quintessential inflationary models and the high-frequency gravitational waves expected by possible laboratory schemes.

Positive definite problem of energy density and radiative energy flux for pulse cylindrical gravitational wave

By using the general expressions of energy-momentum pseudo-tensor of the cylindrical gravitational waves (GW) given by Rosen and Virbhadra in Cartesian coordinates, the concrete forms of energy density and radiative energy flux of the pulse cylindrical GW are obtained. Their physical properties, suitable range and asymptotic behaviour are considered. It is found that: For the region in which space radial coordinates to origin are greater than the pulse width of the pulse cylindrical GW, the energy density and radiative energy flux of the outward travelling pulse cylindrical GW propagating along a light-cone are positive definite. However, for the region in which the space radial coordinates are less than the pulse width, there is no guarantee for the positive definite property of the radiative energy flux of the outward travelling wave. Moreover, we show that the asymptotic behaviour of the energy and energy flux densities of the pulse cylindrical GW and that of the Riemann curvature tensor have good self-consistancy in space-like, time-like and null infinity regions.

Test of Abnormally Large Coherent Scattering Cross Section Using Solar-Neutrino

We have carried out a high precision torsion balance experiment in searching for abnormally large coherent scattering cross sections between a sapphire crystal and solar-neutrino. According to the hypothesis and the experimental results presented by J. Weber, a diurnal effect, which was 60 times larger than the noise level, should be observed obviously, but no significant diurnal effects were found at the level of 8.1 × 10-8 dyn in our experiment.

Electromagnetic Response of High-Frequency Gravitational Waves by Coupling Open Resonant Cavity

We present a new detecting scheme of high-frequency gravitational waves (HFGWs) in the GHz band, the scheme consists of a high-quality-fact or open microwave cavity, a static magnetic field passing through the cavity and an electromagnetic (EM) normal mode stored in the cavity It is found that under the resonant condition first-and second-order perturbation EM effects have almost the same detecting sensitivity to the HFGWs in the GHz band (h ~ 10−26, ν ~ 5 GHz), but the former contains more information from the HFGWs. We also provide a very brief review for possible improving way of the sensitivity This scheme would be highly complementary to other schemes of detecting the HFGWs.

Utilization of Electromagnetic Detector for Selection and Detection of High-Frequency Relic Gravitational Waves

It is shown that coupling system between fractal membranes and a Gaussian beam passing through a static magnetic field has strong selection capability for the stochastic relic gravitational wave background. The relic GW components propagating along the positive direction of the symmetrical axis of the Gaussian beam might generate an optimal electromagnetic perturbation while the perturbation produced by the relic GW components propagating along the negative and perpendicular directions to the symmetrical axis will be much less than the former.The influence of the random fluctuation of the relic GWs to such effect can be neglected and the influence of the random fluctuation of the relic GWs to such effect can be neglected.

Perturbed Effect of the Gravitational Wave Produced by Microwave Electromagnetic Cavity on Detecting Electromagnetic Field

Perturbed effect of high-frequency gravitational radiation produced by microwave electromagnetic (EM) cavity on static detecting EM field is investigated, and corresponding perturbation solutions have been given. It is found that the gravitational wave (GW) beam propagating along symmetric axis of the cavity is purely +type polarized in transverse traceless coordinate system, and it can make the static EM field generate a cumulative perturbed effect which is proportional to the time. For the gravitational radiation wave beams propagating along other directions, they are usually mixed radiation of + and × type polarization. Quality factor of the cavity plays a key role in interaction strength of the GW with the detecting EM field.

Alternative Solutions to Bianchi Type-I Cosmology

We present a class of new exact solutions in string cosmology theory, and the solutions describe a homogeneous but anisotropic plane-symmetric string universe within the framework of Bianchi type-I cosmology. Some solutions previously discussed are included in the class of exact solutions as the special cases. Our result may provide further quantitative description and theoretical basis for the string cosmology model.

Energy-Momentum Pseudo-tensor of Cylindrical Gravitational Waves of Both the Polarized States

According to the Einstein-Tolman expression of the energy-momentum pseudo-tensor (EMPT), we calculate the EMPT of cylindrical gravitational waves (CGW) of both the polarized states (BPS) in cylindrical polar coordinates and Cartesian coordinates. We find that Cartesian coordinates are the more suitable coordinates to describe the CGW of BPS.

High frequency gravitational wave of a composite toroidal electromagnetic resonant system

Starting with the Einstein equation of weak gravitational field, a new scheme of generating high frequency gravitational wave by composite toroidal electromagnetic resonant system is discussed. The system is a composite toroidal electromagnetic resonant cavity consisting of a vacuum and a dielectric regions. In the focal region of the cavity under the condition of allowable ohmic losses in the cavity walls, the amplitude of the standing gravitational wave is almost two orders of magnitude higher than that in usual cavity with the same volume. A concrete numerical calculation shows that a composite toroidal electromagnetic resonant system with a volume 2 × 108 cm3 could generate the standing gravitational wave with an amplitude h = 10-33, wavelength λg = 40 cm in its focal region. This is comparable to the typical order of magnitude of several astrophysical sources, and it would be displayed by electromagnetic detection due to very high frequency.