Optomechanical deformation and strain in elastic dielectrics

Light forces induced by scattering and absorption in elastic dielectrics lead to local density modulations and deformations. These perturbations in turn modify light propagation in the medium and generate an intricate nonlinear response. We generalise an analytic approach where light propagation in one-dimensional media of inhomogeneous density is modelled as a result of multiple scattering between polarizable slices. Using the Maxwell stress tensor formalism we compute the local optical forces and iteratively approach self-consistent density distributions where the elastic back-action balances gradient- and scattering forces. For an optically trapped dielectric we derive the nonlinear dependence of trap position, stiffness and total deformation on the object's size and field configuration. Generally trapping is enhanced by deformation, which exhibits a periodic change between stretching and compression. This strongly deviates from qualitative expectations based on the change of photon momentum of light crossing the surface of a dielectric. We conclude that optical forces have to be treated as volumetric forces and that a description using the change of photon momentum at the surface of a medium is inappropriate

Applications of aerospace technology to petroleum extraction and reservoir engineering

Through contacts with the petroleum industry, the petroleum service industry, universities and government agencies, important petroleum extraction problems were identified. For each problem, areas of aerospace technology that might aid in its solution were also identified, where possible. Some of the problems were selected for further consideration. Work on these problems led to the formulation of specific concepts as candidate for development. Each concept is addressed to the solution of specific extraction problems and makes use of specific areas of aerospace technology

Wave Packet Echoes in the Motion of Trapped Atoms

We experimentally demonstrate and systematically study the stimulated revival (echo) of motional wave packet oscillations. For this purpose, we prepare wave packets in an optical lattice by non-adiabatically shifting the potential and stimulate their reoccurence by a second shift after a variable time delay. This technique, analogous to spin echoes, enables one even in the presence of strong dephasing to determine the coherence time of the wave packets. We find that for strongly bound atoms it is comparable to the cooling time and much longer than the inverse of the photon scattering rate

Environmental magneto-gradiometric marine survey in high anthropic noisy area

We describe the magneto-gradiometric survey performed in the Mar Piccolo of Taranto, Italy in May 2005 for environmental aims. This region, being a noisy harbour environment, provides a challenging test for magnetic methods. To reduce the spurious noise signals, both of temporal and spatial origin, we used two Geometrics G880 caesium magnetometers towed in transverse gradient configuration. We show how in shallow waters this gradiometric configuration allows one to distinguish the anomalies due to small metallic bodies near the seafloor from the induced noise due to anthropic contribution and geomagnetic field variations. A direct visual inspection confirmed that the peculiarities highlighted in the gradient anomaly map were due to abandoned metallic objects founded on the seafloor

Some magnetic evidences of the Ist century BC Salapia harbor near the Margherita di Savoia shoreline, SE Italy

This paper highlights some magnetic evidences revealed by a recent marine magnetic survey ran near the Margherita di Savoia shoreline, Puglia (Italy). The survey has been planned to probe one of the expected settlement site not perused yet. The accurate elaboration of high density total magnetic field intensity data shows some features which can be interpreted as markers of harbor framework, at present time partially uprooted. A model of the bodies which cause the magnetic anomaly is also provided

Atom cooling and trapping by disorder

We demonstrate the possibility of three-dimensional cooling of neutral atoms by illuminating them with two counterpropagating laser beams of mutually orthogonal linear polarization, where one of the lasers is a speckle field, i.e. a highly disordered but stationary coherent light field. This configuration gives rise to atom cooling in the transverse plane via a Sisyphus cooling mechanism similar to the one known in standard two-dimensional optical lattices formed by several plane laser waves. However, striking differences occur in the spatial diffusion coefficients as well as in local properties of the trapped atoms.Comment: 11 figures (postscript

Adiabatic creation of coherent superposition states via multiple intermediate states

We consider an adiabatic population transfer process that resembles the well established stimulated Raman adiabatic passage (STIRAP). In our system, the states have nonzero angular momentums $J$, therefore, the coupling laser fields induce transitions among the magnetic sublevels of the states. In particular, we discuss the possibility of creating coherent superposition states in a system with coupling pattern $J=0\Leftrightarrow J=1$ and $J=1\Leftrightarrow J=2$. Initially, the system is in the J=0 state. We show that by two delayed, overlapping laser pulses it is possible to create any final superposition state of the magnetic sublevels $|2,-2>$, $|2,0>$, $|2,+2>$. Moreover, we find that the relative phases of the applied pulses influence not only the phases of the final superposition state but the probability amplitudes as well. We show that if we fix the shape and the time-delay between the pulses, the final state space can be entirely covered by varying the polarizations and relative phases of the two pulses. Performing numerical simulations we find that our transfer process is nearly adiabatic for the whole parameter set.Comment: 7 pages, 10 figure

A multipurpose X-ray fluorescence scanner developed for in situ analysis

Abstract: Over the time, instrument transportability has become more and more important, especially in Cultural Heritage, as often artworks cannot be moved from their site, either because of the size or due to problems with permission issues, or simply because moving them to a laboratory is physically impossible, as e.g. in the case of mural paintings. For this reason, the INFN-CHNet, the network for Cultural Heritage studies of the Italian National Institute of Nuclear Physics (INFN), has developed an XRF scanner for in situ analyses. The instrument is the result of a wide collaboration, where different units of the network have been developing the diverse parts, then merged in a single system. The XRF scanner has been designed to be a four-season and green instrument. The control/acquisition/analysis software has been fully developed by our group, using only open-source software. Other strong points of the system are easiness of use, high portability, good performances and ultra-low radiation dispersion, which allows us to use even when the public can be present. It can run both with mains or on batteries, in the latter case with a maximum runtime longer than 10 h. It has a very low cost, when compared to commercial systems with equivalent performances, and easily replaceable components, which makes it accessible for a much wider portion of the interested community. The system has been thought and designed as an open system, suitable for further development/improvements, that can result interesting for non-conventional XRF analysis. The CHNet XRF scanner has proved to be really very well suited for applications in the Cultural Heritage field, as testified by the many recent applications. This paper describes the present version of our instrument and reports on the tests performed to characterise its main features.Fil: Taccetti, F.. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Castelli, L.. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Czelusniak, C.. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Gelli, N.. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Mazzinghi, A.. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Palla, L.. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Ruberto, C.. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Censori, C.. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Lo Giudice, A.. Università di Torino; Italia. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Re, A.. Università di Torino; Italia. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Zafiropulos, D.. Istituto Nazionale di Fisica Nucleare; ItaliaFil: Arneodo, F.. New York University Abu Dhab; Emiratos Arabes UnidosFil: Conicella, V.. New York University Abu Dhab; Emiratos Arabes UnidosFil: Di Giovanni, A.. New York University Abu Dhab; Emiratos Arabes UnidosFil: Torres, R.. New York University Abu Dhab; Emiratos Arabes UnidosFil: Castella, F.. Universidad Nacional de San Martín. Instituto de Investigaciones sobre el Patrimonio Cultural; ArgentinaFil: Mastrangelo, Noemi Elisa. Universidad Nacional de San Martín. Instituto de Investigaciones sobre el Patrimonio Cultural; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gallegos, D.. Universidad Nacional de San Martín. Instituto de Investigaciones sobre el Patrimonio Cultural; ArgentinaFil: Tascon, Marcos. Universidad Nacional de San Martín. Instituto de Investigaciones sobre el Patrimonio Cultural; Argentina. Universidad Nacional de San Martín. Instituto de Investigación e Ingeniería Ambiental. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación e Ingeniería Ambiental; ArgentinaFil: Marte, F.. Universidad Nacional de San Martín. Instituto de Investigaciones sobre el Patrimonio Cultural; ArgentinaFil: Giuntini, L.. Università degli Studi di Firenze; Itali

Adiabatic population transfer via multiple intermediate states

This paper discusses a generalization of stimulated Raman adiabatic passage (STIRAP) in which the single intermediate state is replaced by $N$ intermediate states. Each of these states is connected to the initial state \state{i} with a coupling proportional to the pump pulse and to the final state \state{f} with a coupling proportional to the Stokes pulse, thus forming a parallel multi-$\Lambda$ system. It is shown that the dark (trapped) state exists only when the ratio between each pump coupling and the respective Stokes coupling is the same for all intermediate states. We derive the conditions for existence of a more general adiabatic-transfer state which includes transient contributions from the intermediate states but still transfers the population from state \state{i} to state \state{f} in the adiabatic limit. We present various numerical examples for success and failure of multi-$\Lambda$ STIRAP which illustrate the analytic predictions. Our results suggest that in the general case of arbitrary couplings, it is most appropriate to tune the pump and Stokes lasers either just below or just above all intermediate states.Comment: 14 pages, two-column revtex style, 10 figure

Frequency selection by soliton excitation in nondegenerate intracavity downconversion

We show that soliton excitation in intracavity downconversion naturally selects a strictly defined frequency difference between the signal and idler fields. In particular, this phenomenon implies that if the signal has smaller losses than the idler then its frequency is pulled away from the cavity resonance and the idler frequency is pulled towards the resonance and {\em vice versa}. The frequency selection is shown to be closely linked with the relative energy balance between the idler and signal fields.Comment: 5 pages, 3 figures. To appear in Phys Rev Let