Photoassociation with chirped laser pulses: calculation of the absolute number of molecules per pulse

Koch, Christiane P.; Kosloff, Ronnie; Luc‐Koenig, E.; Masnou-Seeuws, F.; Crubellier, A.

doi:10.1088/0953-4075/39/19/s15

Cited by 68 publications

(104 citation statements)

References 33 publications

(48 reference statements)

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“…Representing the Hamiltonian (Eq. 2) on a finite grid in coordinate space allows us to divide the trap volume, V, into many smaller boxes of volume ν box , whose number is larger then the number of atoms, N. Then, following [23], the number of molecules, N mol,J , is computed by:…”

Section: Simulationsmentioning

confidence: 99%

“…To find the molecular formation rate P J for each peak intensity I 0 , we then multiply by the number of chirps per ms and spatially average over the density distribution in the trap and intensity profile of the photoassociation laser. Following [23], we find the overall molecular formation rate by summing over all the partial waves necessary for convergence:…”

Section: Simulationsmentioning

confidence: 99%

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Production of ultracold molecules with chirped nanosecond pulses: Evidence for coherent effects

et al. 2013

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We use frequency-chirped light on the nanosecond time scale to produce ultracold 87 Rb2 molecules in the lowest triplet state via the process of photoassociation. Comparing to quantum simulations of the molecular formation, we conclude that coherent stimulated emission plays an important role and is primarily responsible for the significant difference observed between positive and negative chirps.

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Section: Simulationsmentioning

confidence: 99%

Section: Simulationsmentioning

confidence: 99%

Production of ultracold molecules with chirped nanosecond pulses: Evidence for coherent effects

et al. 2013

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“…A potentially fruitful collaborative venture is the production of ultracold molecules by coherently-controlled photoassociation of ultracold atoms. Despite many theoretical proposals on this topic [4,5,6,7,8,9,10,11], experiments to date [12,13] have demonstrated coherent control of only the photodestruction of ultracold molecules, not of their collisional formation. Here we describe our use of frequency-chirped light on the nanosecond timescale [14] to coherently control ultracold collisions in Rb.…”

mentioning

confidence: 99%

Coherent control of ultracold collisions with chirped light: Direction matters

et al. 2007

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We demonstrate the ability to coherently control ultracold atomic Rb collisions using frequencychirped light on the nanosecond time scale. For certain center frequencies of the chirp, the rate of inelastic trap-loss collisions induced by negatively chirped light is dramatically suppressed compared to the case of a positive chirp. We attribute this to a fundamental asymmetry in the system: an excited wavepacket always moves inward on the attractive molecular potential. For a positive chirp, the resonance condition moves outward in time, while for a negative chirp, it moves inward, in the same direction as the excited wavepacket; this allows multiple interactions between the wavepacket and the light, enabling the wavepacket to be returned coherently to the ground state. Classical and quantum calculations support this interpretation.PACS numbers: 32.80. Qk, 32.80.Pj, 34.50.Rk Traditionally, the fields of ultracold physics [1] and short-pulse coherent control [2, 3] have followed independent paths. Besides the obvious incompatibility of sub-picosecond timescales with the motion of slow atoms, cooling typically deals with translational degrees of freedom while coherent control involves internal degrees of freedom. A potentially fruitful collaborative venture is the production of ultracold molecules by coherently-controlled photoassociation of ultracold atoms. Despite many theoretical proposals on this topic [4,5,6,7,8,9,10,11], experiments to date [12,13] have demonstrated coherent control of only the photodestruction of ultracold molecules, not of their collisional formation. Here we describe our use of frequency-chirped light on the nanosecond timescale [14] to coherently control ultracold collisions in Rb. We observe significant differences in the collision rates for the two chirp directions. For the negative chirp, a wavepacket excited to the attractive molecular potential can subsequently be returned coherently to the ground state, thereby reducing the collision rate.Ultracold molecules [15] are of significant current interest due to potential applications in a variety of fields: ultracold chemistry, quantum computing, novel quantum degenerate systems, and tests of fundamental symmetries. One method of ultracold molecule production is photoassociation [16], where two ultracold atoms collide in the presence of laser light and undergo a free-to-bound transition to form an excited molecule. Spontaneous emission can subsequently produce ultracold molecules in the electronic ground state, but typically in a distribution of high vibrational levels. If the entire process could be done coherently, it might be possible to populate a * Present address:

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“…The application of linear chirps, for example, is expected to increase the excitation efficiency of the free bound transition in the perturbative regime [12,43,44,45,46] by adiabatic transfer. Also the nuclear dynamics can be influenced by imprinting the field's phase onto a coherent vibrational wavepacket in the excitation.…”

Section: Influence Of Linear Chirpmentioning

confidence: 99%

Photoassociation and coherent transient dynamics in the interaction of ultracold rubidium atoms with shaped femtosecond pulses. I. Experiment

et al. 2009

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We experimentally investigate various processes present in the photoassociative interaction of an ultracold atomic sample with shaped femtosecond laser pulses. We demonstrate the photoassociation of pairs of rubidium atoms into electronically excited, bound molecular states using spectrally cut femtosecond laser pulses tuned below the rubidium D1 or D2 asymptote. Time-resolved pumpprobe spectra reveal coherent oscillations of the molecular formation rate, which are due to coherent transient dynamics in the electronic excitation. The oscillation frequency corresponds to the detuning of the spectral cut position to the asymptotic transition frequency of the rubidium D1 or D2 lines, respectively. Measurements of the molecular photoassociation signal as a function of the pulse energy reveal a non-linear dependence and indicate a non-perturbative excitation process. Chirping the association laser pulse allowed us to change the phase of the coherent transients. Furthermore, a signature for molecules in the electronic ground state is found, which is attributed to molecule formation by femtosecond photoassociation followed by spontaneous decay. In a subsequent article [A. Merli et al., submitted] quantum mechanical calculations are presented, which compare well with the experimental data and reveal further details about the observed coherent transient dynamics.

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Photoassociation with chirped laser pulses: calculation of the absolute number of molecules per pulse

Cited by 68 publications

References 33 publications

Production of ultracold molecules with chirped nanosecond pulses: Evidence for coherent effects

Production of ultracold molecules with chirped nanosecond pulses: Evidence for coherent effects

Coherent control of ultracold collisions with chirped light: Direction matters

Photoassociation and coherent transient dynamics in the interaction of ultracold rubidium atoms with shaped femtosecond pulses. I. Experiment

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