Geophysical studies with laser-beam detectors of gravitational waves

The existing high technology laser-beam detectors of gravitational waves may find very useful applications in an unexpected area - geophysics. To make possible the detection of weak gravitational waves in the region of high frequencies of astrophysical interest, ~ 30 - 10^3 Hz, control systems of laser interferometers must permanently monitor, record and compensate much larger external interventions that take place in the region of low frequencies of geophysical interest, ~ 10^{-5} - 3 X 10^{-3} Hz. Such phenomena as tidal perturbations of land and gravity, normal mode oscillations of Earth, oscillations of the inner core of Earth, etc. will inevitably affect the performance of the interferometers and, therefore, the information about them will be stored in the data of control systems. We specifically identify the low-frequency information contained in distances between the interferometer mirrors (deformation of Earth) and angles between the mirrors' suspensions (deviations of local gravity vectors and plumb lines). We show that the access to the angular information may require some modest amendments to the optical scheme of the interferometers, and we suggest the ways of doing that. The detailed evaluation of environmental and instrumental noises indicates that they will not prevent, even if only marginally, the detection of interesting geophysical phenomena. Gravitational-wave instruments seem to be capable of reaching, as a by-product of their continuous operation, very ambitious geophysical goals, such as observation of the Earth's inner core oscillations.Comment: 29 pages including 8 figures, modifications and clarifications in response to referees' comments, to be published in Class. Quant. Gra

Strong-field approximation for Coulomb explosion of H_2^+ by short intense laser pulses

We present a simple quantum mechanical model to describe Coulomb explosion of H$_2^+$ by short, intense, infrared laser pulses. The model is based on the length gauge version of the molecular strong-field approximation and is valid for pulses shorter than 50 fs where the process of dissociation prior to ionization is negligible. The results are compared with recent experimental results for the proton energy spectrum [I. Ben-Itzhak et al., Phys. Rev. Lett. 95, 073002 (2005), B. D. Esry et al., Phys. Rev. Lett. 97, 013003 (2006)]. The predictions of the model reproduce the profile of the spectrum although the peak energy is slightly lower than the observations. For comparison, we also present results obtained by two different tunneling models for this process.Comment: 8 pages, 4 figure

Analytical modeling for the heat transfer in sheared flows of nanofluids

We developed a model for the enhancement of the heat flux by spherical and elongated nano- particles in sheared laminar flows of nano-fluids. Besides the heat flux carried by the nanoparticles the model accounts for the contribution of their rotation to the heat flux inside and outside the particles. The rotation of the nanoparticles has a twofold effect, it induces a fluid advection around the particle and it strongly influences the statistical distribution of particle orientations. These dynamical effects, which were not included in existing thermal models, are responsible for changing the thermal properties of flowing fluids as compared to quiescent fluids. The proposed model is strongly supported by extensive numerical simulations, demonstrating a potential increase of the heat flux far beyond the Maxwell-Garnet limit for the spherical nanoparticles. The road ahead which should lead towards robust predictive models of heat flux enhancement is discussed.Comment: 14 pages, 10 figures, submitted to PR

Capture into Rydberg states and momentum distributions of ionized electrons

The yield of neutral excited atoms and low-energy photoelectrons generated by the electron dynamics in the combined Coulomb and laser field after tunneling is investigated. We present results of Monte-Carlo simulations built on the two-step semiclassical model, as well as analytic estimates and scaling relations for the population trapping into the Rydberg states. It is shown that mainly those electrons are captured into bound states of the neutral atom that due to their initial conditions (i) have moderate drift momentum imparted by the laser field and (ii) avoid strong interaction ("hard" collision) with the ion. In addition, it is demonstrated that the channel of capture, when accounted for in semiclassical calculations, has a pronounced effect on the momentum distribution of electrons with small positive energy. For the parameters that we investigated its presence leads to a dip at zero momentum in the longitudinal momentum distribution of the ionized electrons.Comment: 9 pages, 8 figures in one zip-archiv

Wavelength and intensity dependence of multiple forward scattering at above-threshold ionization in mid-infrared strong laser fields

The nonperturbative role of multiple forward scattering for Coulomb focusing in mid-infrared laser fields and its dependence on a laser intensity and wavelength are investigated for low-energy photoelectrons at above-threshold ionization. We show that high-order rescattering events can have comparable contributions to the Coulomb focusing and the effective number of rescattering depends weakly on laser parameters in the classical regime. However, the relative contribution of the forward scattering to the Coulomb focusing and the Coulomb focusing in total decrease with the rise of the laser intensity and wavelength

Search for astro-gravity correlations

A new approach in the gravitational wave experiment is considered. In addition to the old method of searching for coincident reactions of two separated gravitational antennae it was proposed to seek perturbations of the gravitational detector noise background correlated with astrophysical events such as neutrino and gamma ray bursts which can be relaibly registered by correspondent sensors. A general algorithm for this approach is developed. Its efficiency is demonstrated in reanalysis of the old data concerning the phenomenon of neutrino-gravity correlation registered during of SN1987A explosion.Comment: 29 pages (LaTeX), 4 figures (EPS

The Physics of Kondo Impurities in Graphene

This article summarizes our understanding of the Kondo effect in graphene, primarily from a theoretical perspective. We shall describe different ways to create magnetic moments in graphene, either by adatom deposition or via defects. For dilute moments, the theoretical description is in terms of effective Anderson or Kondo impurity models coupled to graphene's Dirac electrons. We shall discuss in detail the physics of these models, including their quantum phase transitions and the effect of carrier doping, and confront this with existing experimental data. Finally, we point out connections to other quantum impurity problems, e.g., in unconventional superconductors, topological insulators, and quantum spin liquids.Comment: 27 pages, 8 figs. Review article prepared for Rep. Prog. Phys. ("key issues" section). (v2) Final version as publishe