Search results for "Physics::Optics"
showing 10 items of 1958 documents
Dynamical quantum repeater using cavity-QED and optical coherent states
2013
In the framework of cavity QED, we propose a quantum repeater scheme that uses coherent light and atoms coupled to optical cavities. In contrast to conventional schemes, we exploit solely the cavity QED evolution for the entire quantum repeater scheme and, thus, avoid any explicit execution of quantum logical gates. The entanglement distribution between the repeater nodes is realized with the help of pulses of coherent light interacting with the atom-cavity system in each repeater node. In our previous paper [D. Gonta and P. van Loock, Phys. Rev. A 86, 052312 (2012)], we already proposed a dynamical protocol to purify a bipartite entangled state using the evolution of atomic chains coupled …
Spatial separation of atomic states in a laser-cooled ion crystal
1998
A laser cooled ion crystal containing several hundred Ca+ ions has been stored in a linear Paul trap. Cooling is provided by a red detund laser at the 4S1/2−4P1/2 resonance transition. A second laser serves for repumping of those ions which decay from the excited 4P1/2 level to the metastable 3D3/2 state. The ions can be additionally excited by a third laser to a long lived metastable 3D5/2 energy level which decouples them from the cooling laser radiation. The light pressure acting upon the laser cooled ions pushes them into the direction of the laser beam. The ions in the metastable 3D5/2 state, however, do not experience any light pressure force and diffuse to the crystal side which poin…
PhoXonic Whispering Gallery Mode Resonators: parametrical optomechanic oscillations and its applications
2021
We report on the experimental analysis of parametrical optomechanical oscillations and photo-acoustical applications such as flow cytometers in hollow phoxonic whispering gallery mode resonators. Both phenomena can be enchanced or suppressed and showed chaotic behavior.
Near Field of Strongly Coupled Plasmons: Uncovering Dark Modes
2012
Strongly coupled plasmons in a system of individual gold nanoparticles placed at subnanometer distance to a gold film (nanoparticle-on-plane, NPOP) are investigated using two complementary single particle spectroscopy techniques. Optical scattering spectroscopy exclusively detects plasmon modes that couple to the far field via their dipole moment (bright modes). By using photoemission electron microscopy (PEEM), we detect in the identical NPOPs near-field modes that do not couple to the scattered far field (dark modes) and are characterized by a strongly enhanced nonlinear electron emission process. To our knowledge, this is the first time that both far- and near-field spectroscopy are carr…
Numerical study on the limit of quasi-static approximation for plasmonic nanosphere
2019
Plasmonic nanospheres are often employed as resonant substrates in many nanophotonic applications, like in enhanced spectroscopy, near-field microscopy, photovoltaics, and sensing. Accurate calculation and tuning of optical responses of such nanospheres are essential to achieve optimal performance. Mie theory is widely used to calculate optical properties of spherical particles. Although, an approximated version of Mie approach, the quasi-static approximation (QSA) can also be used to determine the very same properties of those spheres with a lot simpler formulations. In this work, we report our numerical study on the limit and accuracy of QSA with respect to the rigorous Mie approach. We c…
Intensity-Based Single Particle Plasmon Sensing.
2021
Plasmon sensors respond to local changes of their surrounding environment with a shift in their resonance wavelength. This response is usually detected by measuring light scattering spectra to determine the resonance wavelength. However, single wavelength detection has become increasingly important because it simplifies the setup, increases speed, and improves statistics. Therefore, we investigated theoretically how the sensitivity toward such single wavelength scattering intensity changes depend on the material and shape of the plasmonic sensor. Surprisingly, simple equations describe this intensity sensitivity very accurately and allow us to distinguish the various contributions: Rayleigh…
Light self-confinement via second harmonic generation in a 2D nonlinear photonic crystal waveguide
2007
Spatial solitary waves induced by quadratic nonlinearities have been the subject of many theoretical and experimental investigations in the last decade, with extensive studies being devoted to soliton formation in 1D nonlinear photonic crystals (NPC) such as PPLN (periodically poled LiNbO3). Here we present results on a new class of (1 + 1)D spatial solitary waves, the first examples of quadratic self-confinement in a 2D NPC.
The use of maximum entropy statistics combined with simulation methods to determine the structure of 4-dimethylamino-3-cyanobiphenyl
1997
Abstract 4-dimethylamino-3-cyanobiphenyl (4-DMA-3-CB) was characterised with respect to non-linear optical (NLO) properties in the gas phase and in the crystal. The crystal structure was solved from a series of electron diffraction patterns using both molecular modelling and ab initio maximum entropy techniques combined with log-likelihood evaluation. The agreement between the two methods is excellent and the structure evaluation permits an analysis of the major components of the hyperpolarisability tensor in the crystal framework.
Rogue waves among noiselike-pulse laser emission: An experimental investigation
2014
We investigate experimental conditions in a fiber ring laser where noiselike-pulse emission fulfills the rogue wave criteria, highlighting the influence of the chromatic dispersion sign as well as the pivotal role of the pulse measurement design. While pulse-energy rogue waves are exclusively detected in the anomalous dispersion regime, spectral rogue waves are recorded for both positive and negative dispersions. To reveal $\mathsf{L}\text{-shaped}$ statistical series compatible with the generation of spectral rogue wave events, the dispersive Fourier-transform method is implemented to study the shot-to-shot spectral fluctuations of the laser output.
The role of auxiliary states in state discrimination with linear optical evices
2001
The role of auxiliary photons in the problem of identifying a state secretly chosen from a given set of L-photon states is analyzed. It is shown that auxiliary photons do not increase the ability to discriminate such states by means of a global measurement using only optical linear elements, conditional transformation and auxiliary photons.