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Ignacio R. Sola - One of the best experts on this subject based on the ideXlab platform.

  • State-Selective Excitation of Quantum Systems via Geometrical Optimization.
    Journal of chemical theory and computation, 2015
    Co-Authors: Bo Y. Chang, Seokmin Shin, Ignacio R. Sola
    Abstract:

    We lay out the foundations of a general method of quantum control via geometrical optimization. We apply the method to state-Selective Population Transfer using ultrashort transform-limited pulses between manifolds of levels that may represent, e.g., state-Selective transitions in molecules. Assuming that certain states can be prepared, we develop three implementations: (i) preoptimization, which implies engineering the initial state within the ground manifold or electronic state before the pulse is applied; (ii) postoptimization, which implies engineering the final state within the excited manifold or target electronic state, after the pulse; and (iii) double-time optimization, which uses both types of time-ordered manipulations. We apply the schemes to two important dynamical problems: To prepare arbitrary vibrational superposition states on the target electronic state and to select weakly coupled vibrational states. Whereas full Population inversion between the electronic states only requires control at initial time in all of the ground vibrational levels, only very specific superposition states can be prepared with high fidelity by either pre- or postoptimization mechanisms. Full state-Selective Population inversion requires manipulating the vibrational coherences in the ground electronic state before the optical pulse is applied and in the excited electronic state afterward, but not during all times.

  • Selective photodissociation in diatomic molecules by dynamical Stark-shift control.
    The Journal of chemical physics, 2008
    Co-Authors: Hyeonho Choi, Bo Y. Chang, Won-joon Son, Seokmin Shin, Ignacio R. Sola
    Abstract:

    Selective Population Transfer in electronic states of dissociative molecular systems is illustrated by adopting a control scheme based on Stark-chirped rapid adiabatic passage (SCRAP). In contrast to the discrete N-level system, dynamical Stark shift is induced in a more complex manner in the molecular electronic states. Wavepacket dynamics on the light-induced potentials, which are determined by the detuning of the pump pulse, can be controlled by additional Stark pulse in the SCRAP scheme. Complete Population Transfer can be achieved by either lowering the energy barrier along the adiabatic passage or placing the initial wavepacket on a well-defined dressed state suitable for the control. The determination of the pulse sequence is sufficient for controlling Population Transfer to the target state.

  • Controlling Non-Franck−Condon Transitions: Counterintuitive Schemes of Population Transfer in the Adiabatic and Strong Adiabatic Regimes†
    The Journal of Physical Chemistry A, 2003
    Co-Authors: Vladimir S. Malinovsky, Jesuś Santamaría, Ignacio R. Sola
    Abstract:

    Vibrationally Selective Population Transfer in electronic transitions involving small Franck-Condon factors is studied by means of two-photon excitation with pulse sequences applied in counterintutive order. Depending on the intensity of the pulses, two schemes allow ultrafast adiabatic passage. Both schemes, called STIRAP and APLIP, are analyzed as a function of the geometry of the electronic states and of the time duration and intensity of the pulses that drive the transitions. Although both schemes imply adiabatic following, the APLIP scheme requires pulses of considerably larger intensity than STIRAP, hence operating in a strong adiabatic regime. Simple adiabatic criteria for high-quality Transfer are proposed, and analytic proofs are provided that show under which conditions STIRAP and APLIP converge. The results of this paper are illustrated with numerical simulations for two different electronic transitions in the Na 2 molecule.

  • Transferring vibrational Population between electronic states of diatomic molecules via light-induced-potential shaping
    The Journal of Chemical Physics, 2001
    Co-Authors: Bo Y. Chang, Vladimir S. Malinovsky, Ignacio R. Sola, Jesus Santamaria, Jeffrey L. Krause
    Abstract:

    We investigate two-photon, Selective excitation of diatomic molecules with intense, ultrafast laser pulses. The method involves Transfer of a vibrational Population between two electronic states by shaping of light-induced potentials (LIPs). Creation and control of the LIPs is accomplished by choosing pairs of transform-limited pulses with proper frequency detunings and time delays. Depending on the sequence of pulses (intuitive or counter-intuitive) and on the sign of the detuning (below or above the first transition) four schemes are possible for Population Transfer by LIP shaping. We develop a simple analytic model to predict the optimal laser pulses, and to model the adiabatic dynamics in the different schemes. Based on a harmonic, three-state model of the sodium dimer we demonstrate numerically that all four schemes can lead to efficient, Selective Population Transfer. A careful analysis of the underlying physical mechanisms reveals the varying roles played by the adiabatic and diabatic crossings of the LIPs. The detailed mechanisms influence the robustness and experimental applicability of the schemes.

  • Selective excitation of vibrational states by shaping of light-induced potentials
    Physical review letters, 2000
    Co-Authors: Ignacio R. Sola, Vladimir S. Malinovsky, Bo Y. Chang, Jesus Santamaria, Jeffrey L. Krause
    Abstract:

    In this Letter we describe a method for Population Transfer using intense, ultrafast laser pulses. The selectivity is accomplished by careful shaping of light-induced potentials (LIPs). Creation and control of the LIPs is accomplished by choosing pairs of pulses with proper frequency detunings and time delays. As an example, Selective Population Transfer is demonstrated for a three-state model of the sodium dimer.

Thomas Halfmann - One of the best experts on this subject based on the ideXlab platform.

  • Stark-chirped rapid adiabatic passage among a three-state molecular system: Experimental and numerical investigations
    Physical Review A, 2008
    Co-Authors: Martin Oberst, Holger Münch, G. Grigoryan, Thomas Halfmann
    Abstract:

    We present extended experimental investigations and numerical studies on coherently driven Population inversion in a three-state molecular quantum system by sequential double-Stark-chirped rapid adiabatic passage (SCRAP) (D-SCRAP) and three-state-SCRAP (T-SCRAP). D-SCRAP and T-SCRAP are alternative extensions of SCRAP. In D-SCRAP and T-SCRAP, a $\ensuremath{\Lambda}$-type quantum system is coherently driven by two laser pulses, the pump and Stokes pulses, which are slightly detuned from transition frequencies. A third strong laser pulse induces dynamic Stark shifts of the relevant transitions. If the timing of the three pulses is appropriately chosen, the quantum system is prepared to almost complete Population inversion between the two lower states in the $\ensuremath{\Lambda}$-type level scheme. The Transfer process is robust with regard to fluctuations of experimental parameters, provided some limitations are met. The paper presents convincing experimental data on D-SCRAP and T-SCRAP, driving efficient and Selective Population Transfer to a highly excited vibrational level in nitrous oxide (NO) molecules. T-SCRAP yields Transfer efficiencies of up to 95%. The efficiency of T-SCRAP is almost uneffected by the limited lifetime of the intermediate state in the $\ensuremath{\Lambda}$ system. The paper also presents data on the accurate experimental determination of Rabi frequencies and Stark shifts. This involves measurements of power broadening, Autler-Townes splittings, and Stark-shifted spectral lines in NO molecules. Moreover, we discuss the calibration of absolute Transfer efficiences by comparison with stimulated emission pumping. The experimental data are confirmed by extended numerical simulations. The simulations also serve to intensively study the properties and dynamics of D-SCRAP and T-SCRAP.

  • Population inversion by retroreflection-induced bichromatic adiabatic passage (RIBAP)
    2005
    Co-Authors: A. Peralta Conde, Jens Klein, Martin Oberst, Thomas Halfmann
    Abstract:

    Over the past decades coherent interactions have provided a powerful tool for the efficient and robust manipulation of Population distributions in quantum systems. While incoherent excitations suffer from limited Population Transfer efficiencies and low selectivities, coherent techniques canaccomplish complete and Selective Population Transfer between bound states. We present a new coherent technique based on the bichromatic excitation of bound quantum systems, which produces a complete adiabatic passage between bound states. In this technique a single laser beam intersects twice, e.g., by retroreflection, a supersonic particle beam slightly tilted away from normal incidence, thereby inducing Doppler shifts of the resonance between the initial and target state. The retroreflected beam should be parallel to the incident beam, attenuated and slightly delayed. Under these conditions, it can be shown 1 that complete and robust Population Transfer between can be achieved. The experimental 2

  • source of metastable h 2s atoms using the stark chirped rapid adiabatic passage technique
    Physical Review A, 1999
    Co-Authors: L P Yatsenko, K. Bergmann, Thomas Halfmann, Bruce W. Shore, Amichay Vardi
    Abstract:

    We propose the use of Stark chirped rapid-adiabatic-passage method, a technique in which the energy of a target state is swept through resonance by a slowly varying dynamic Stark shift to induce complete Population Transfer from the ground 1s state to the metastable 2 s state of the hydrogen atom. Parasitic ionization processes are strongly reduced by using a two-color excitation scheme. Our detailed numerical calculations show that under judicious choice of pulse parameters, up to 98% of the Population can be found in the 2 s state at the end of the process. @S1050-2947~99!51112-8# PACS number~s!: 42.50.Md Control of Population Transfer between specific quantum states has been a major goal in atomic and molecular physics during the last three decades. The recent availability of efficient schemes for Selective Population Transfer, such as the stimulated Raman adiabatic passage ~STIRAP! technique, have opened new directions in collision dynamics and spectroscopy @1#. One important aim of Selective Population Transfer is to provide pure and dense sources of excited atoms. The preparation of hydrogen atoms in their metastable 2s state is of particular interest due to the long lifetime ~provided the electric field is small! and high energy of this state. Furthermore, hydrogen lends itself to quantitatively accurate theoretical analysis. However, application of STIRAP to the Transfer of Population from the 1 s to the 2s state of hydrogen requires coupling to a higher electronic state. The required wavelength to access this state must be less than 120 nm. In this range, radiation with suitable intensity and coherence is not currently available. A prerequisite for the construction of a pure H(2 s) source is the development of more efficient Population Transfer schemes, as current optical Population Transfer methods are limited, by photoionization, to an efficiency of less than 20%@2#. Recently we have developed a Population Transfer scheme called ‘‘Stark chirped rapid adiabatic passage’’ ~SCRAP !@ 3#. This technique builds on the well-known method of rapid adiabatic passage @4‐8# in which a one- or two-photon transition between two discrete-energy states is adiabatically swept through resonance, thereby inducing a nearly complete Population inversion. Our method utilizes one laser pulse ~the ‘‘pump’’ !, tuned slightly away from resonance with the two-photon transition between the states, and a second pulse ~the ‘‘Stark’’ ! that sweeps through the resonance by inducing a dynamic Stark shift. The result is similar to the Population inversion reported by Loy @8#, who used adiabatic quasistatic pulses of ;5-ms duration, to induce dc Stark shifts. However, he induced two sequential Population inversions per pulse ~an excitation for the leading edge and deexcitation for the trailing edge of each pulse!, with the final result that no net Population Transfer took place. In SCRAP a time delay between the ‘‘Stark’’ pulse and the ‘‘pump’’ pulse ensures that only one Transfer process occurs and that the entire Population is in the excited state when the process is over. Commercially available pulsed lasers enable the completion of the inversion process within a few nanoseconds with the SCRAP method. Shaping quasistatic pulses of this duration is a much more difficult task. It may also be argued that femtosecond chirping techniques could be used to sweep the resonance. However, the bandwidth of ns pulses is far too small to apply traditional short-pulse methods @9#. The SCRAP method was demonstrated successfully for the 2s-3s transition in metastable helium @3#. In this Rapid Communication, we present a theoretical study of the SCRAP scheme, as applied to produce metastable H(2s) atoms by coherent Population inversion from ground-state ensembles. The excitation scheme is modified from our experiment in He* to a two-color pump pulse in order to avoid unwanted ionization from the 2s state. We study the inversion efficiency as a function of the relative intensities of the two pump pulses and their detuning from two-photon resonance, and show that by appropriate choice of parameters, nearly complete Population inversion is obtained.

Stuart A. Rice - One of the best experts on this subject based on the ideXlab platform.

  • A model study of assisted adiabatic Transfer of Population in the presence of collisional dephasing
    The Journal of chemical physics, 2015
    Co-Authors: Shumpei Masuda, Stuart A. Rice
    Abstract:

    Previous studies have demonstrated that when experimental conditions generate non-adiabatic dynamics that prevents highly efficient Population Transfer between states of an isolated system by stimulated Raman adiabatic passage (STIRAP), the addition of an auxiliary counter-diabatic field (CDF) can restore most or all of that efficiency. This paper examines whether that strategy is also successful in a non-isolated system in which the energies of the states fluctuate, e.g., when a solute is subject to collisions with solvent. We study Population Transfer in two model systems: (i) the three-state system used by Demirplak and Rice [J. Chem. Phys. 116, 8028 (2002)] and (ii) a four-state system, derived from the simulation studies of Demirplak and Rice [J. Chem. Phys. 125, 194517 (2006)], that mimics HCl in liquid Ar. Simulation studies of the vibrational manifold of HCl in dense fluid Ar show that the collision induced vibrational energy level fluctuations have asymmetric distributions. Representations of these asymmetric energy level fluctuation distributions are used in both models (i) and (ii). We identify three sources of degradation of the efficiency of STIRAP generated Selective Population Transfer in model (ii): too small pulse areas of the laser fields, unwanted interference arising from use of strong fields, and the vibrational detuning. For both models (i) and (ii), our examination of the efficiency of STIRAP + CDF Population Transfer under the influence of the asymmetric distribution of the vibrational energy fluctuations shows that there is a range of field strengths and pulse durations under which STIRAP + CDF control of Population Transfer has greater efficiency than does STIRAP generated Population Transfer.

  • Variations on adiabatic passage in optical control of molecular processes
    Journal of Modern Optics, 2004
    Co-Authors: Jiangbin Gong, Stuart A. Rice
    Abstract:

    A number of variations on adiabatic passage for the realization of efficient and Selective Population Transfer in both the gas and liquid phases are presented. The advantageous use of decaying quantum states and/or the influence of continuous measurements during the Population Transfer are stressed and an intriguing adiabatic passage scheme, which is sensitive to the relative phases of the control laser fields, is introduced.

  • Optical control of molecular dynamics in a liquid
    The Journal of Chemical Physics, 2002
    Co-Authors: Mustafa Demirplak, Stuart A. Rice
    Abstract:

    We report the results of a study of the influence of solvent fluctuations on the efficiency of Selective Population Transfer from an initial state to a designated target state of a solute molecule. Our model of the influence of liquid fluctuations on the states of the solute assumes that dephasing is the dominant relaxation process, and utilizes an analog of the Kubo stochastic theory of line shape. The solvent fluctuations are represented as a Gaussian random process that independently modulates each of the energy levels of the solute molecule. For typical liquid densities the maximum amplitude of these fluctuations is taken to be of the order of 150 cm−1, and the correlation time of the fluctuations is taken to be of the order of a few hundred femtoseconds, but we have also explored the effects of varying the fluctuation frequency and correlation time. It is shown that STIRAP (stimulated Raman adiabatic passage) generated Population Transfer to a designated target state of the solute remains efficient w...

  • Sensitivity of the Extended STIRAP Method of Selective Population Transfer to Coupling to Background States
    The Journal of Physical Chemistry B, 2001
    Co-Authors: Vandana Kurkal And, Stuart A. Rice
    Abstract:

    The Kobrak-Rice extended STIRAP approach for Selective Population Transfer has been tested for robustness vis a vis coupling to background states by examining preferential Transfer to one or the other of nearly degenerate target states in the thiophosgene molecule. The calculations were carried out first within the original Kobrak-Rice five state scheme and then with inclusion of successively larger numbers of background states that have off-resonance radiative coupling with the original five states. Population Transfers were calculated with and without use of the rotating wave approximation to determine if inclusion of the background states degraded the accuracy of that approximation. It is shown that the Selective Population Transfer to a particular one of a pair of degenerate states is insensitive to the couplings with the background states and to the use of the rotating wave approximation.

Bo Y. Chang - One of the best experts on this subject based on the ideXlab platform.

  • State-Selective Excitation of Quantum Systems via Geometrical Optimization.
    Journal of chemical theory and computation, 2015
    Co-Authors: Bo Y. Chang, Seokmin Shin, Ignacio R. Sola
    Abstract:

    We lay out the foundations of a general method of quantum control via geometrical optimization. We apply the method to state-Selective Population Transfer using ultrashort transform-limited pulses between manifolds of levels that may represent, e.g., state-Selective transitions in molecules. Assuming that certain states can be prepared, we develop three implementations: (i) preoptimization, which implies engineering the initial state within the ground manifold or electronic state before the pulse is applied; (ii) postoptimization, which implies engineering the final state within the excited manifold or target electronic state, after the pulse; and (iii) double-time optimization, which uses both types of time-ordered manipulations. We apply the schemes to two important dynamical problems: To prepare arbitrary vibrational superposition states on the target electronic state and to select weakly coupled vibrational states. Whereas full Population inversion between the electronic states only requires control at initial time in all of the ground vibrational levels, only very specific superposition states can be prepared with high fidelity by either pre- or postoptimization mechanisms. Full state-Selective Population inversion requires manipulating the vibrational coherences in the ground electronic state before the optical pulse is applied and in the excited electronic state afterward, but not during all times.

  • Selective photodissociation in diatomic molecules by dynamical Stark-shift control.
    The Journal of chemical physics, 2008
    Co-Authors: Hyeonho Choi, Bo Y. Chang, Won-joon Son, Seokmin Shin, Ignacio R. Sola
    Abstract:

    Selective Population Transfer in electronic states of dissociative molecular systems is illustrated by adopting a control scheme based on Stark-chirped rapid adiabatic passage (SCRAP). In contrast to the discrete N-level system, dynamical Stark shift is induced in a more complex manner in the molecular electronic states. Wavepacket dynamics on the light-induced potentials, which are determined by the detuning of the pump pulse, can be controlled by additional Stark pulse in the SCRAP scheme. Complete Population Transfer can be achieved by either lowering the energy barrier along the adiabatic passage or placing the initial wavepacket on a well-defined dressed state suitable for the control. The determination of the pulse sequence is sufficient for controlling Population Transfer to the target state.

  • Transferring vibrational Population between electronic states of diatomic molecules via light-induced-potential shaping
    The Journal of Chemical Physics, 2001
    Co-Authors: Bo Y. Chang, Vladimir S. Malinovsky, Ignacio R. Sola, Jesus Santamaria, Jeffrey L. Krause
    Abstract:

    We investigate two-photon, Selective excitation of diatomic molecules with intense, ultrafast laser pulses. The method involves Transfer of a vibrational Population between two electronic states by shaping of light-induced potentials (LIPs). Creation and control of the LIPs is accomplished by choosing pairs of transform-limited pulses with proper frequency detunings and time delays. Depending on the sequence of pulses (intuitive or counter-intuitive) and on the sign of the detuning (below or above the first transition) four schemes are possible for Population Transfer by LIP shaping. We develop a simple analytic model to predict the optimal laser pulses, and to model the adiabatic dynamics in the different schemes. Based on a harmonic, three-state model of the sodium dimer we demonstrate numerically that all four schemes can lead to efficient, Selective Population Transfer. A careful analysis of the underlying physical mechanisms reveals the varying roles played by the adiabatic and diabatic crossings of the LIPs. The detailed mechanisms influence the robustness and experimental applicability of the schemes.

  • Selective excitation of vibrational states by shaping of light-induced potentials
    Physical review letters, 2000
    Co-Authors: Ignacio R. Sola, Vladimir S. Malinovsky, Bo Y. Chang, Jesus Santamaria, Jeffrey L. Krause
    Abstract:

    In this Letter we describe a method for Population Transfer using intense, ultrafast laser pulses. The selectivity is accomplished by careful shaping of light-induced potentials (LIPs). Creation and control of the LIPs is accomplished by choosing pairs of pulses with proper frequency detunings and time delays. As an example, Selective Population Transfer is demonstrated for a three-state model of the sodium dimer.

Klaas Bergmann - One of the best experts on this subject based on the ideXlab platform.

  • Stimulated Raman adiabatic passage in physics, chemistry, and beyond
    Reviews of Modern Physics, 2017
    Co-Authors: Nikolay V. Vitanov, Andon A. Rangelov, Bruce W. Shore, Klaas Bergmann
    Abstract:

    The technique of stimulated Raman adiabatic passage (STIRAP), which allows efficient and Selective Population Transfer between quantum states without suffering loss due to spontaneous emission, was introduced in 1990 (Gaubatz \emph{et al.}, J. Chem. Phys. \textbf{92}, 5363, 1990). Since then STIRAP has emerged as an enabling methodology with widespread successful applications in many fields of physics, chemistry and beyond. This article reviews the many applications of STIRAP emphasizing the developments since 2000, the time when the last major review on the topic was written (Vitanov \emph{et al.}, Adv. At. Mol. Opt. Phys. \textbf{46}, 55, 2001). A brief introduction into the theory of STIRAP and the early applications for Population Transfer within three-level systems is followed by the discussion of several extensions to multi-level systems, including multistate chains and tripod systems. The main emphasis is on the wide range of applications in atomic and molecular physics (including atom optics, cavity quantum electrodynamics, formation of ultracold molecules, precision experiments, etc.), quantum information (including single- and two-qubit gates, entangled-state preparation, etc.), solid-state physics (including processes in doped crystals, nitrogen-vacancy centers, superconducting circuits, etc.), and even some applications in classical physics (including waveguide optics, frequency conversion, polarization optics, etc.). Promising new prospects for STIRAP are also presented (including processes in optomechanics, detection of parity violation in molecules, spectroscopy of core-nonpenetrating Rydberg states, and Population Transfer with X-ray pulses).

  • Efficient coherent Population Transfer in NO‐molecules using pulsed lasers
    AIP Conference Proceedings, 1995
    Co-Authors: S. Steuerwald, S. Schiemann, Axel Kuhn, Klaas Bergmann
    Abstract:

    Highly efficient and Selective Population Transfer in NO molecules in the electronic ground state (X2Π1/2) from the vibrational level v‘=0 to the level v‘=6 is demonstrated. A rather generally applicable scheme for complete control over the level Population in atoms and molecules is now available. The efficiency relies on a counter‐intuitive interaction sequence of two lasers with the molecule in a process of stimulated Raman scattering involving adiabatic passage (STIRAP).

  • Efficient coherent Population Transfer in NO molecules using pulsed lasers.
    Physical review letters, 1993
    Co-Authors: S. Schiemann, S. Steuerwald, Axel Kuhn, Klaas Bergmann
    Abstract:

    Highly efficient and Selective Population Transfer in NO molecules in the electronic ground state (X 2 Π 1/2 ) from the vibrational level υ''=0 to the level υ''=6 is demonstrated. It shows, for the first time with pulsed lasers, that a rather generally applicable scheme for complete control over the level Population in atoms and molecules is now available. The efficiency relies on a counterintuitive interaction sequence of two lasers with the molecule in a process of stimulated Raman scattering involving adiabatic passage