Search results for "Laser beams"
showing 10 items of 56 documents
Macroscopic jumps of the axial angular momentum variance of a bidimensionally trapped ion
2001
Abstract The time evolution of the axial angular momentum [Lcirc] z of an ion confined in a bidimensional trap is investigated. We find that, under suitable initial conditions, the interaction of the ion with two properly configured classical laser beams induces a peculiar dynamical behaviour of the axial angular momentum fluctuations. We show, in fact, that there exists an instant of time at which the variance of [Lcirc] z undergoes variations proportional to N 2 further to a change of one quantum only in the initial total number N ≫ 1 of vibrational quanta. The non-classical origin of these macroscopic jumps is brought to the light and carefully discussed.
Generation of vector dark-soliton trains by induced modulational instability in a highly birefringent fiber
1999
International audience; We present a set of experimental observations that demonstrate the generation of vector trains of dark-soliton pulses in the orthogonal axes of a highly birefringent optical fiber. We generated dark-soliton trains with terahertz repetition rate in the normal group-velocity dispersion regime by inducing a polarization modulational instability by mixing two intense, orthogonal continuous laser beams. Numerical solutions of the propagation equations were used to optimize the emission of vector dark pulses at the fiber output.
Diffractive pulse-front tilt for low-coherence digital holography
2010
We use a diffractive lens to generate the proper pulse-front-tilt to record full-field off-axis holograms with a 10fs laser source. We experimentally demonstrate optical sectioning of three-dimensional samples with a resolution of about 5 microns.
Photodetachment ofH−in the presence of a low-frequency laser field
1993
The photodetachment of a model one-electron ion simulating ${\mathrm{H}}^{\mathrm{\ensuremath{-}}}$ in the presence of a low-frequency field is analyzed. Two different geometries are considered in order to get information on the effect of the ponderomotive energy shift \ensuremath{\Delta} on the photodetachment cross section. Our calculations suggest that a correspondence may be established between the ponderomotive shift and the photodetachment cross section, when the ejected electron may exchange only a few low-frequency photons. This is in qualitative agreement with recent experimental observations. When a large number of processes are open in which the detached electron may exchange low…
Polarization Domain Wall Solitons with Counterpropagating Laser Beams
1998
The coupling between two intense laser beams in a nonlinear dielectric leads to a host of physical effects. In particular, the interaction between the polarization states of two counterpropagating ligth beams may generate polarization domain wall (PDW7) solitons [1]. We present what we believe is the first experimental observation of PDW7 soliton formation in a nonlinear dielectric medium.
Atom-photon, atom-atom and photon-photon entanglement preparation via fractional adiabatic passage
2004
We propose a relatively robust scheme to generate maximally entangled states of (i) an atom and a cavity photon, (ii) two atoms in their ground states, and (iii) two photons in two spatially separate high-Q cavities. It is based on the interaction via fractional adiabatic passage of a three-level atom traveling through a cavity mode and a laser beam. The presence of optical phases is emphasized.
Decoherence-free creation of atom-atom entanglement in cavity via fractional adiabatic passage
2005
We propose a robust and decoherence insensitive scheme to generate controllable entangled states of two three-level atoms interacting with an optical cavity and a laser beam. Losses due to atomic spontaneous transitions and to cavity decay are efficiently suppressed by employing fractional adiabatic passage and appropriately designed atom-field couplings. In this scheme the two atoms traverse the cavity-mode and the laser beam in opposite directions as opposed to other entanglement schemes in which the atoms are required to have fixed locations inside a cavity. We also show that the coherence of a traveling atom can be transferred to the other one without populating the cavity-mode.
Topologically Protected Twist Edge States for a Resonant Mechanical Laser-Beam Scanner
2019
We design a one-dimensional chain of two different alternating three-dimensional elastic chiral unit cells. The chain’s topological band gap, a result of the alternation of unit cells combined with their chirality and an effective mirror symmetry, guarantees a protected edge state, corresponding to a localized twist mode with an eigenfrequency inside the one-dimensional band gap. A small axial modulation at the one end of the beam can excite this resonant twist mode at the other end of the beam, via evanescent modes in the gap. The topological robustness of the edge state allows us to add a micromirror to the other end of the beam, turning the arrangement into a resonant mechanical laser-be…
Potential scattering transitions in a strong chaotic non-Markovian radiation field.
1989
Theorie non relativiste de la diffusion par un potentiel en presence d'un champ laser intense, fluctuant en amplitude et en phase, a l'approximation de Born. Calcul des largeurs et profils de raies et des facteurs de coherence en fonction de l'intensite du laser
Two-photon spectroscopy of mercury and velocity-selective double resonances
2009
Two-photon laser spectroscopy of the $6\text{ }{^{1}S}_{0}\ensuremath{-}7\text{ }{^{1}S}_{0}$ transition in mercury has been performed using two copropagating continuous-wave laser beams. One laser beam is at 254 nm wavelength and can be tuned to the $6\text{ }{^{1}S}_{0}\ensuremath{-}6\text{ }{^{3}P}_{1}$ resonance. The other laser beam is at 408 nm. Two very different regimes can be distinguished, one far off resonance and one near resonance with the one-photon resonance. A resonance which is not Doppler broadened has been observed for low Rabi frequencies. This velocity-selective double resonance in a three-level ladder system is analogous to the dark resonance in three-level $\ensuremat…