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Search Results: 1 - 10 of 223808 matches for " R. Ciurylo "
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Optical tuning of the scattering length of cold alkaline earth atoms
R. Ciurylo,E. Tiesinga,P. S. Julienne
Physics , 2004, DOI: 10.1103/PhysRevA.71.030701
Abstract: It is possible to tune the scattering length for the collision of ultra-cold 1S0 ground state alkaline-earth atoms using an optical Feshbach resonance. This is achieved with a laser far detuned from an excited molecular level near the frequency of the atomic intercombination 1S0--3P1 transition. Simple resonant scattering theory, illustrated by the example of 40Ca, allows an estimate of the magnitude of the effect. Unlike alkali metal species, large changes of the scattering length are possible while atom loss remains small, because of the very narrow line width of the molecular photoassociation transition. This raises prospects for control of atomic interactions for a system without magnetically tunable Feshbach resonance levels.
Photoassociation spectroscopy of cold alkaline earth atoms near the intercombination line
R. Ciurylo,E. Tiesinga,S. Kotochigova,P. S. Julienne
Physics , 2004, DOI: 10.1103/PhysRevA.70.062710
Abstract: The properties of photoassociation (PA) spectra near the intercombination line (the weak transition between $^{1}S_{0}$ and $^{3}P_{1}$ states) of group II atoms are theoretically investigated. As an example we have carried out a calculation for Calcium atoms colliding at ultra low temperatures of 1 mK, 1 $\mu$K, and 1 nK. Unlike in most current photoassociation spectroscopy the Doppler effect can significantly affect the shape of the investigated lines. Spectra are obtained using Ca--Ca and Ca--Ca$^*$ short-range {\it ab initio} potentials and long-range van der Waals and resonance dipole potentials. The similar van der Waals coefficients of ground $^{1}S_{0} + ^{1}S_{0}$ and excited $^{1}S_{0} + ^{3}P_{1}$ states cause the PA to differ greatly from those of strong, allowed transitions with resonant dipole interactions. The density of spectral lines is lower, the Condon points are at relatively short range, and the reflection approximation for the Franck-Condon factors is not applicable, and the spontaneous decay to bound ground-state molecules is efficient. Finally, the possibility of efficient production of cold molecules is discussed.
Line shapes of optical Feshbach resonances near the intercombination transition of bosonic Ytterbium
M. Borkowski,R. Ciurylo,P. S. Julienne,S. Tojo,K. Enomoto,Y. Takahashi
Physics , 2009,
Abstract: The properties of bosonic Ytterbium photoassociation spectra near the intercombination transition $^{1}S_{0}$--$^{3}P_{1}$ are studied theoretically at ultra low temperatures. We demonstrate how the shapes and intensities of rotational components of optical Feshbach resonances are affected by mass tuning of the scattering properties of the two colliding ground state atoms. Particular attention is given to the relationship between the magnitude of the scattering length and the occurrence of shape resonances in higher partial waves of the van der Waals system. We develop a mass scaled model of the excited state potential that represents the experimental data for different isotopes. The shape of the rotational photoassociation spectrum for various bosonic Yb isotopes can be qualitatively different.
Narrow Line Photoassociation in an Optical Lattice
T. Zelevinsky,M. M. Boyd,A. D. Ludlow,T. Ido,J. Ye,R. Ciurylo,P. Naidon,P. S. Julienne
Physics , 2006, DOI: 10.1103/PhysRevLett.96.203201
Abstract: With ultracold $^{88}$Sr in a 1D magic wavelength optical lattice, we performed narrow line photoassociation spectroscopy near the $^1$S$_0 - ^3$P$_1$ intercombination transition. Nine least-bound vibrational molecular levels associated with the long-range $0_u$ and $1_u$ potential energy surfaces were measured and identified. A simple theoretical model accurately describes the level positions and treats the effects of the lattice confinement on the line shapes. The measured resonance strengths show that optical tuning of the ground state scattering length should be possible without significant atom loss.
Two-color photoassociation spectroscopy of ytterbium atoms and the precise determinations of s-wave scattering lengths
Masaaki Kitagawa,Katsunari Enomoto,Kentaro Kasa,Yoshiro Takahashi,Roman Ciurylo,Pascal Naidon,Paul S. Julienne
Physics , 2007, DOI: 10.1103/PhysRevA.77.012719
Abstract: By performing high-resolution two-color photoassociation spectroscopy, we have successfully determined the binding energies of several of the last bound states of the homonuclear dimers of six different isotopes of ytterbium. These spectroscopic data are in excellent agreement with theoretical calculations based on a simple model potential, which very precisely predicts the s-wave scattering lengths of all 28 pairs of the seven stable isotopes. The s-wave scattering lengths for collision of two atoms of the same isotopic species are 13.33(18) nm for ^{168}Yb, 3.38(11) nm for ^{170}Yb, -0.15(19) nm for ^{171}Yb, -31.7(3.4) nm for ^{172}Yb, 10.55(11) nm for ^{173}Yb, 5.55(8) nm for ^{174}Yb, and -1.28(23) nm for ^{176}Yb. The coefficient of the lead term of the long-range van der Waals potential of the Yb_2 molecule is C_6=1932(30) atomic units $(E_h a_0^6 \approx 9.573\times 10^{-26}$ J nm^6).
Absolute Frequency Measurement of Rubidium 5S-7S Two-Photon Transitions
Piotr Morzynski,Piotr Wcislo,Piotr Ablewski,Rafal Gartman,Wojciech Gawlik,Piotr Maslowski,Bartlomiej Nagorny,Filip Ozimek,Czeslaw Radzewicz,Marcin Witkowski,Roman Ciurylo,Michal Zawada
Physics , 2013, DOI: 10.1364/OL.38.004581
Abstract: We report the absolute frequency measurements of rubidium 5S-7S two-photon transitions with a cw laser digitally locked to an atomic transition and referenced to an optical frequency comb. The narrow, two-photon transition, 5S-7S (760 nm) insensitive to first order in a magnetic field, is a promising candidate for frequency reference. The performed tests yield the transition frequency with accuracy better than reported previously.
Absolute measurement of the ${}^{1}S_{0}$ - ${}^{3}P_{0}$ clock transition in neutral ${}^{88}$Sr over the 330 km-long stabilized fibre optic link
Piotr Morzynski,Marcin Bober,Dobroslawa Bartoszek-Bober,Jerzy Nawrocki,Przemyslaw Krehlik,Lukasz Sliwczynski,Marcin Lipinski,Piotr Maslowski,Agata Cygan,Piotr Dunst,Michal Garus,Daniel Lisak,Jerzy Zachorowski,Wojciech Gawlik,Czeslaw Radzewicz,Roman Ciurylo,Michal Zawada
Physics , 2015, DOI: 10.1038/srep17495
Abstract: We report a stability below $7\times 10{}^{-17}$ of two independent optical lattice clocks operating with bosonic ${}^{88}$Sr isotope. The value (429228066418008.3(1.9)${}_{syst}$(0.9)${}_{stat}$~Hz) of the absolute frequency of the ${}^{1}S_{0}$ - ${}^{3}P_{0}$ transition was measured with an optical frequency comb referenced to the local representation of the UTC by the 330 km-long stabilized fibre optical link. The result was verified by series of measurements on two independent optical lattice clocks and agrees with recommendation of Bureau International des Poids et Mesures.
Power Aware Routing Protocol (PARP) for Wireless Sensor Networks  [PDF]
R. Prema, R. Rangarajan
Wireless Sensor Network (WSN) , 2012, DOI: 10.4236/wsn.2012.45019
Abstract: Several wireless sensor network applications ought to decide the intrinsic variance between energy efficient communication and the requirement to attain preferred quality of service (QoS) such as packet delivery ratio, delay and to reduce the power consumption of wireless sensor nodes. In order to address this challenge, we propose the Power Aware Routing Protocol (PARP), which attains application-specified communication delays at low energy cost by dynamically adapting transmission power and routing decisions. Extensive simulation results prove that the proposed PARP attains better QoS and reduced power consumption.
An Innovative Low Cost EM Pollution Measurement System  [PDF]
R. Sittalatchoumy, R. Seetharaman
Circuits and Systems (CS) , 2016, DOI: 10.4236/cs.2016.78176
Abstract: Mobile phones and other electronic devices are emitting radiations that will provide harmful effects to the human health. In order to measure the radiation, an innovative low cost measurement system is proposed in this paper. The ideology is to simplify the circuit’s value by converting a voltage detecting circuit to a field detecting circuit by finding an optimum resistance on trial and error basis. The requirement for a trial and error technique is to not allow too high or too low resistance which can be either short or open, resulting provides more damage to the circuit.
Ant Lion Optimization Approach for Load Frequency Control of Multi-Area Interconnected Power Systems  [PDF]
R. Satheeshkumar, R. Shivakumar
Circuits and Systems (CS) , 2016, DOI: 10.4236/cs.2016.79206
Abstract: This work proposes a novel nature-inspired algorithm called Ant Lion Optimizer (ALO). The ALO algorithm mimics the search mechanism of antlions in nature. A time domain based objective function is established to tune the parameters of the PI controller based LFC, which is solved by the proposed ALO algorithm to reach the most convenient solutions. A three-area interconnected power system is investigated as a test system under various loading conditions to confirm the effectiveness of the suggested algorithm. Simulation results are given to show the enhanced performance of the developed ALO algorithm based controllers in comparison with Genetic Algorithm (GA), Particle Swarm Optimization (PSO), Bat Algorithm (BAT) and conventional PI controller. These results represent that the proposed BAT algorithm tuned PI controller offers better performance over other soft computing algorithms in conditions of settling times and several performance indices.
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