E. Luc-Koenig

Publications (6)1.88 Total impact

• Article: Femtosecond pulses and dynamics of molecular photoexcitation: RbCs example

  B. E. Londono, A. Derevianko, J. E. Mahecha, A. Crubellier, E. Luc-Koenig
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  ABSTRACT: We investigate the dynamics of molecular photoexcitation by unchirped femtosecond laser pulses using RbCs as a model system. This study is motivated by a goal of optimizing a two-color scheme of transferring vibrationally-excited ultracold molecules to their absolute ground state. In this scheme the molecules are initially produced by photoassociation or magnetoassociation in bound vibrational levels close to the first dissociation threshold. We analyze here the first step of the two-color path as a function of pulse intensity from the low-field to the high-field regime. We use two different approaches, a global one, the 'Wavepacket' method, and a restricted one, the 'Level by Level' method where the number of vibrational levels is limited to a small subset. The comparison between the results of the two approaches allows one to gain qualitative insights into the complex dynamics of the high-field regime. In particular, we emphasize the non-trivial and important role of far-from-resonance levels which are adiabatically excited through 'vertical' transitions with a large Franck-Condon factor. We also point out spectacular excitation blockade due to the presence of a quasi-degenerate level in the lower electronic state. We conclude that selective transfer with femtosecond pulses is possible in the low-field regime only. Finally, we extend our single-pulse analysis and examine population transfer induced by coherent trains of low-intensity femtosecond pulses.
  03/2012;
• Article: Application of B-splines in determining the eigenspectrum of diatomic molecules: robust numerical description of halo-state and Feshbach molecules

  A Derevianko, E Luc-Koenig, F Masnou-Seeuws
  Can. J. Phys. 01/2009; 87:67-74.
• Source

  Available from: Andrei Derevianko

  Article: Application of B-splines to determining eigen-spectrum of Feshbach molecules

  A. Derevianko, E. Luc-Koenig, F. Masnou-Seeuws
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  ABSTRACT: The B-spline basis set method is applied to determining the rovibrational eigen-spectrum of diatomic molecules. A particular attention is paid to a challenging numerical task of an accurate and efficient description of the vibrational levels near the dissociation limit (halo-state and Feshbach molecules). Advantages of using B-splines are highlighted by comparing the performance of the method with that of the commonly-used discrete variable representation (DVR) approach. Several model cases, including the Morse potential and realistic potentials with 1/R^3 and 1/R^6 long-range dependence of the internuclear separation are studied. We find that the B-spline method is superior to the DVR approach and it is robust enough to properly describe the Feshbach molecules. The developed numerical method is applied to studying the universal relation of the energy of the last bound state to the scattering length. We numerically illustrate the validity of the quantum-defect-theoretic formulation of such a relation for a 1/R^6 potential. Comment: submitted to can j phys: Walter Johnson symposum
  06/2008;
• Source

  Available from: ubc.ca

  Conference Proceeding: Formation of stable ultracold molecules by photoassociation with chirped laser pulses

  C.P. Koch, E. Luc-Koenig, F. Masnou-Seeuws
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  ABSTRACT: We investigate photoassociation of ultracold atoms, such as Cs(6s), with chirped laser pulses in the ps range. Numerical calculations are analyzed, demonstrating efficient population inversion within a photoassociation window. Stabilization of the photoassociated molecules into bound levels of the ground state is discussed. Ongoing work on photoassociation of rubidium with femtosecond pulses will be presented at the conference.
  Quantum Electronics and Laser Science Conference, 2005. QELS '05; 06/2005
• Source

  Available from: Ronnie Kosloff

  Article: Photoassociation of cold atoms with chirped laser pulses: time-dependent calculations and analysis of the adiabatic transfer within a two-state model

  E. Luc-Koenig, R. Kosloff, F. Masnou-Seeuws, M. Vatasescu
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  ABSTRACT: This theoretical paper presents numerical calculations for photoassociation of ultracold cesium atoms with a chirped laser pulse and detailed analysis of the results. In contrast with earlier work, the initial state is represented by a stationary continuum wavefunction. In the chosen example, it is shown that an important population transfer is achieved to $\approx 15$ vibrational levels in the vicinity of the v=98 bound level in the external well of the $0_g^-(6s+6p_{3/2})$ potential. Such levels lie in the energy range swept by the instantaneous frequency of the pulse, thus defining a ``photoassociation window''. Levels outside this window may be significantly excited during the pulse, but no population remains there after the pulse. Finally, the population transfer to the last vibrational levels of the ground $a^3\Sigma_u^+$(6s + 6s) is significant, making stable molecules. The results are interpreted in the framework of a two state model as an adiabatic inversion mechanism, efficient only within the photoassociation window. The large value found for the photoassociation rate suggests promising applications. The present chirp has been designed in view of creating a vibrational wavepacket in the excited state which is focussing at the barrier of the double well potential. Comment: 49 pages, 9 figures, submitted to Phys. Rev. A
  04/2004;
• Article: Lu-Fano plots for potentials with non-Coulomb tails: application to vibrational spectra of long-range diatomic molecules

  V N Ostrovsky, V Kokoouline, E Luc-Koenig, F Masnou-Seeuws
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  ABSTRACT: The multichannel quantum defect theory was originally developed for potentials with Coulomb asymptotic behavior. Generalization to non-Coulombic potentials was focused on the representation of the scattering observables in terms of a pair of functions solution of the radial equation in the long-range region. We show how one of the basic tools of quantum defect theory, namely the method to construct the famous Lu-Fano plots (Lu K T and Fano U 1970 Phys. Rev. A 2 81), can be extended to the potentials with general non-Coulomb asymptotes by considering only the law linking the energies and asymptotic phases to the quantum numbers. This provides an efficient method for the analysis of molecular spectra close to dissociation limit, generalizing the Le Roy-Bernstein approach to two coupled channels.
  Journal of Physics B Atomic Molecular and Optical Physics 01/2001; 34(2):L27. · 1.88 Impact Factor