Search results for "fluid"
showing 10 items of 5513 documents
Purely long-range polar molecules composed of identical lanthanide atoms
2019
International audience; Doubly polar molecules, possessing an electric dipole moment and a magnetic dipole moment, can strongly couple to both an external electric field and a magnetic field, providing unique opportunities to exert full control of the system quantum state at ultracold temperatures. We propose a method for creating a purely long-range doubly polar homonuclear molecule from a pair of strongly magnetic lanthanide atoms, one atom being in its ground level and the other in a superposition of quasi-degenerate opposite-parity excited levels [Phys. Rev. Lett. 121, 063201 (2018)]. The electric dipole moment is induced by coupling the excited levels with an external electric field. W…
Contour detection based on nonlinear discrete diffusion in a cellular nonlinear network
2001
International audience; A contour detection based on a diffusive cellular nonlinear network is proposed. It is shown that there exists a particular nonlinear function for which, numerically, the obtained contour is satisfactory. Furthermore, this nonlinear function can be achieved using analog components.
Diffusion effects in a nonlinear electrical lattice
1998
International audience; We consider a nonlinear electrical network modeling the generalized Nagumo equation. Focusing on the particular case where the initial load of the lattice consists in the superimposition of a coherent information weakly varying in space and a perturbation of small amplitude, we show that the perturbation can be eliminated quickly, almost without disturbing the information.
Short-length storage of intense optical pulses in solid by adiabatic passage
2009
We propose a novel scheme of storage of intense pulses which allows a significant reduction of the storage length with respect to standard schemes. This scheme is particularly adapted to store optical information in media with fast relaxations.
Unified kinetic formulation of incoherent waves propagating in nonlinear media with noninstantaneous response
2010
This article presents a unified kinetic formulation of partially coherent nonlinear optical waves propagating in a noninstantaneous response Kerr medium. We derive a kinetic equation that combines the weak Langmuir turbulence kinetic equation and a Vlasov-like equation within a general framework: It describes the evolution of the spectrum of a random field that exhibits a quasistationary statistics in the presence of a noninstantaneous nonlinear response. The kinetic equation sheds new light on the dynamics of partially coherent nonlinear waves and allows for a qualitative interpretation of the interplay between the noninstantaneous nonlinearity and the nonstationary statistics of the incoh…
Induction mechanisms in a von Kármán swirling flows of liquid Gallium
2004
International audience; Using in situ magnetic field measurements, we study the induction mechanisms in a swirling flow of liquid Gallium generated inside a cylinder, in the gap between two coaxial rotating discs. The von Kármán flow generated in this manner has both helicity and differential rotation. Magnetic Reynolds numbers Rm up to 7 (based on the disc rim speed) are generated. We study the magnetic induction when an external field is applied successively along the axis, in the azimuthal direction or tranverse to the axis of rotation. In the first two cases, both the flow and the magnetic field are axisymmetric, and an effective mechanism of conversion from poloidal to toroidal field e…
Collisional models in a nonperturbative approach
1992
Abstract A nonperturbative method set forth recently for handling quantum dynamics in the intermediate regime (far from either the sudden or the adiabatic limit) is applied to soluble two-state collisional models.
STABILITY AND SPECTRA OF SMALL 3He-4He CLUSTERS
2005
Diffusion Monte Carlo calculations have been systematically performed to analyze the stability of small mixed 3 He -4 He clusters, as well as their excitation spectra. The picture that emerges is that of systems with strong shell effects whose binding and excitation energies are essentially determined by the monopole properties of an effective Hamiltonian.
Driven harmonic oscillators in the adiabatic Magnus approximation
1993
The time evolution of driven harmonic oscillators is determined by applying the Magnus expansion in the basis set of instantaneous eigenstates of the total Hamiltonian. It is shown that the first-order approximation already provides transition probabilities close to the exact values even in the intermediate regime.
Stable control of pulse speed in parametric three-wave solitons.
2006
International audience; We analyze the control of the propagation speed of three wave packets interacting in a medium with quadratic nonlinearity and dispersion. We find analytical expressions for mutually trapped pulses with a common velocity in the form of a three-parameter family of solutions of the three-wave resonant interaction. The stability of these novel parametric solitons is simply related to the value of their common group velocity.