Optimal control of photoassociation of cold atoms and photodissociation of long-range molecules: Characteristic times for wave-packet propagation

Vatasescu, Mihaela; Dulieu, Olivier; Kosloff, Ronnie; Masnou-Seeuws, F.

doi:10.1103/physreva.63.033407

Cited by 31 publications

(39 citation statements)

References 38 publications

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“…On the opposite, in a precedent paper [19] studying the photoassociation with a continuous laser in the electronic state 1 g (6s + 6p 3/2 ) of Cs 2 , at R L = 90 a 0 and for a temperature T = 125 µK, we have shown that a gaussian wavepacket having a large radial width and a small momentum p 0 is spreading more rapidly than it is mov-ing; being quite difficult to gain insight on the relevant dynamics by using it, a possible choice is to consider a much smaller spatial width, implying a bigger momentum width. Components with much bigger momenta are then introduced in the representation of the initial state, falsifying the dynamics in the corresponding channel.…”

Section: Evaluation Of the Initial Density Matrix By Gaussian Wavepacmentioning

confidence: 99%

“…The width ∆R of the radial density distribution is related to the momentum spread for the relative motion by ∆R∆p R ≈h 2 , then depending on the temperature [18,19].…”

Section: Evaluation Of the Initial Density Matrix By Gaussian Wavepacmentioning

confidence: 99%

“…An evaluation of the initial density matrix by gaussian wavepackets can be valid for sufficiently low laser detunings δ at L (very large distance R) and sufficiently high temperatures T [18,19]. On the contrary, at very low temperatures and for the photoassociation in more profound vibrational states of the excited molecular potential, the potential energy V g (R)…”

Section: Introductionmentioning

confidence: 99%

“…Theoretically, several time-dependent studies of photoassociation in the ultracold regime have been proposed [16,17,18,19,20].…”

Section: Introductionmentioning

confidence: 99%

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Optimizing the photoassociation of cold atoms by use of chirped laser pulses

2004

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Abstract. Photoassociation of ultracold atoms induced by chirped picosecond pulses is analyzed in a nonperturbative treatment by following the wavepackets dynamics on the ground and excited surfaces. The initial state is described by a Boltzmann distribution of continuum scattering states. The chosen example is photoassociation of cesium atoms at temperature T=54 µK from the a 3 Σ + u (6s, 6s) continuum to bound levels in the external well of the 0 − g (6s + 6p 3/2 ) potential. We study how the modification of the pulse characteristics (carrier frequency, duration, linear chirp rate and intensity) can enhance the number of photoassociated molecules and suggest ways of optimizing the production of stable molecules.

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Section: Evaluation Of the Initial Density Matrix By Gaussian Wavepacmentioning

confidence: 99%

“…The width ∆R of the radial density distribution is related to the momentum spread for the relative motion by ∆R∆p R ≈h 2 , then depending on the temperature [18,19].…”

Section: Evaluation Of the Initial Density Matrix By Gaussian Wavepacmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Theoretically, several time-dependent studies of photoassociation in the ultracold regime have been proposed [16,17,18,19,20].…”

Section: Introductionmentioning

confidence: 99%

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Optimizing the photoassociation of cold atoms by use of chirped laser pulses

2004

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“…Laser cooling and evaporative cooling of atoms [1] and the coherent control of excitation processes in molecules [2,3] represent prime examples. The possibility of combining these two areas, i.e., applying coherent control techniques to ultracold systems, has generated a great deal of interest, especially in the context of using short laser pulses to produce ultracold molecules by photoassociating ultracold atoms [4,5,6,7,8,9,10,11,12,13,14,15]. Part of the appeal is the prospect of controlling the internal state distribution of the resulting molecules.…”

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confidence: 99%

Probing ultracold collisional dynamics with frequency-chirped pulses

et al. 2006

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We report on the dynamics of ultracold collisions induced by near-resonant frequency-chirped light. A series of identical chirped pulses, separated by a variable delay, is applied to an ultracold sample of 85 Rb, and the rate of inelastic trap-loss collisions is measured. For small detunings of the chirped light below the atomic resonance, we observe that the rate of collisions induced by a given pulse can be increased by the presence of an earlier pulse. We attribute this to the enhancement of short-range collisional flux by the long-range excitation of atom pairs to an attractive molecular potential. For larger detunings and short delays, we find that a leading pulse can suppress the rate of collisions caused by a following pulse. This is due to a depletion of short-range atom pairs by the earlier pulse. Comparison of our data to classical Monte-Carlo simulations of the collisions yields reasonable agreement. Recent years have witnessed enhanced capabilities in controlling both the external and internal degrees of freedom of atoms and molecules. Laser cooling and evaporative cooling of atoms [1] and the coherent control of excitation processes in molecules [2,3] represent prime examples. The possibility of combining these two areas, i.e., applying coherent control techniques to ultracold systems, has generated a great deal of interest, especially in the context of using short laser pulses to produce ultracold molecules by photoassociating ultracold atoms [4,5,6,7,8,9,10,11,12,13,14,15]. Part of the appeal is the prospect of controlling the internal state distribution of the resulting molecules. Understanding and controlling the dynamics of the formation process will be key to these efforts. In the present work, we explore the nanosecond time-scale dynamics of a closelyrelated process: ultracold atomic collisions induced by frequency-chirped light [16], shown in Fig. 1. By varying the delay between successive pulses of chirped light, we observe that the collisions induced by a given pulse can be either enhanced or suppressed by the presence of a preceding pulse, depending on the range of frequencies spanned by the chirp. If the chirp encompasses frequencies close to the atomic resonance, long-range excitation to the R −3 potential (R is the internuclear separation) leads to collisional flux enhancement. For chirps centered well below the atomic resonance, efficient adiabatic excitation by the first chirp depletes the short-range atom pairs available to be excited by the second chirp.A number of previous experiments [6,17,18,19,20] have employed time-dependent excitation with fixedfrequency light to investigate dynamical effects in ultracold atomic interactions. The frequency-chirped light utilized in the present work is unique in two important ways [16]: 1) the chirp provides adiabatic, and therefore * Present address: Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria very efficient, excitation of atom pairs; and 2) the wide range of frequencies spanned by the c...

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Low-dimensional electronic states at silicon surfaces

Crain

Himpsel

2005

Appl. Phys. A

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Optimal control of photoassociation of cold atoms and photodissociation of long-range molecules: Characteristic times for wave-packet propagation

Cited by 31 publications

References 38 publications

Optimizing the photoassociation of cold atoms by use of chirped laser pulses

Optimizing the photoassociation of cold atoms by use of chirped laser pulses

Probing ultracold collisional dynamics with frequency-chirped pulses

Low-dimensional electronic states at silicon surfaces

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