Search results for " Optics"
showing 10 items of 5880 documents
Faraday patterns in low-dimensional Bose-Einstein condensates
2004
We show that Faraday patterns can be excited in the weak confinement space of low-dimensional Bose-Einstein condensates by temporal modulation of the trap width, or equivalently of the trap frequency Omega_tight, in the tight confinement space. For slow modulation, as compared with Omega_tight, the low-dimensional dynamics of the condensate in the weak confinement space is described by a Gross-Pitaevskii equation with time modulated nonlinearity coefficient. For increasing modulation frequencies a noticeable reduction of the pattern formation threshold is observed close to 2*Omega_tight, which is related to the parametric excitation of the internal breathing mode in the tight confinement sp…
ADIABATIC COOLING OF IONS IN THE PENNING TRAP
1991
An ion cloud in a Penning trap can be cooled by adiabatic expansion by reducing the trap's magnetic and electric fields. We treat the ion cloud as a classical gas and obtain the relations between the temperature and the trapping fields. This cooling method may be useful in trapping and cooling of antiprotons with the aim of measuring the gravitational accleration of anti-protons and other experiments on heavy ions.
Vortex replication in Bose-Einstein condensates trapped in double-well potentials
2009
In this work we demonstrate, by means of numerical simulations, the possibility of replicating matter-wave vortices in a Bose-Einstein condensate trapped in a double-well potential. The most remarkable result is the generation of replicas of an initial vortex state located in one side of the double potential, which evolves into two copies, each one located in one of the potential minima. A simple linear theory gives the basic explanation of the phenomenon and predicts experimental realistic conditions for observation. A complementary strategy of easy experimental implementation to dramatically decrease the replication time is presented and numerically tested for the general case of nonlinea…
Observation of the condensation of classical waves
2010
We report a theoretical, numerical and experimental study of condensation of classical optical waves. The condensation of observed directly, as a function of nonlinearity and wave kinetic energy, in a self-defocusing photorefractive crystal.
Condensation of classical optical waves
2010
We demonstrate the nonlinear condensation of classical optical waves. The condensation is observed directly, as a function of nonlinearity and wave kinetic energy, in a self-defocusing photorefractive crystal.
Collective behavior ofMbosonic modes interacting with a single two-level atom
1988
The Hamiltonian describing, without the rotating-wave approximation (RWA), the linear interaction between M bosonic modes with an Einstein spectrum and a single two-level atom is exactly and canonically transformed introducing M suitable collective independent field modes, in such a way that only one among them is coupled to the atom. Some physical consequences of this fact are analyzed and, in particular, the existence of radiation-trapping phenomena together with the possibility of atomic absorption suppression is established. The applicability of the RWA to this system is discussed and the importance of the effective-field statistics for the time evolution of the system is pointed out.
Formation of self-trapped excitons through stimulated recombination of radiation-induced primary defects in alkali halides
1998
Abstract A self-trapped exciton formation through photostimulated recombination of an F and an H center — the exciton-created primary defect pair, is proposed and experimentally examined in alkali halides at low temperatures.
Entanglement control in hybrid optomechanical systems
2012
We demonstrate the control of entanglement in a hybrid optomechanical system comprising an optical cavity with a mechanical end-mirror and an intracavity Bose-Einstein condensate (BEC). Pulsed laser light (tuned within realistic experimental conditions) is shown to induce an almost sixfold increase of the atom-mirror entanglement and to be responsible for interesting dynamics between such mesoscopic systems. In order to assess the advantages offered by the proposed control technique, we compare the time-dependent dynamics of the system under constant pumping with the evolution due to the modulated laser light.
Dispersive optical interface based on nanofiber-trapped atoms.
2011
We dispersively interface an ensemble of one thousand atoms trapped in the evanescent field surrounding a tapered optical nanofiber. This method relies on the azimuthally-asymmetric coupling of the ensemble with the evanescent field of an off-resonant probe beam, transmitted through the nanofiber. The resulting birefringence and dispersion are significant; we observe a phase shift per atom of $\sim$\,1\,mrad at a detuning of six times the natural linewidth, corresponding to an effective resonant optical density per atom of 0.027. Moreover, we utilize this strong dispersion to non-destructively determine the number of atoms.
Simulating quantum-optical phenomena with cold atoms in optical lattices
2010
We propose a scheme involving cold atoms trapped in optical lattices to observe different phenomena traditionally linked to quantum-optical systems. The basic idea consists of connecting the trapped atomic state to a non-trapped state through a Raman scheme. The coupling between these two types of atoms (trapped and free) turns out to be similar to that describing light–matter interaction within the rotating-wave approximation, the role of matter and photons being played by the trapped and free atoms, respectively. We explain in particular how to observe phenomena arising from the collective spontaneous emission of atomic and harmonic oscillator samples, such as superradiance and directiona…