Coherent Transients in the Femtosecond Photoassociation of Ultracold Molecules

Salzmann, Wenzel; Mullins, Terry; Eng, J.; Albert, Magnus; Wester, Roland; Weidemüller, Matthias; Merli, A.; Weber, Stefan; Sauer, Franziska; Plewicki, Mateusz; Weise, Fabian; Wöste, L.; Lindinger, Albrecht

doi:10.1103/physrevlett.100.233003

Cited by 59 publications

(82 citation statements)

References 22 publications

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“…Simply increasing the laser intensity and atom-molecule Rabi frequency does not necessarily offer a solution because transfer of population to noncondensate atomic states becomes dominant at high laser coupling [8,[14][15][16][17][18][19]. (This limitation is analogous to spontaneous Raman scattering in two-color PA.) Coherent wave-function dynamics have been observed with broadband, femtosecond PA excitation in a thermal Rb gas [30], but the coherence between the molecule and atom fields was not discussed.As pointed out in Ref. [8], the parameter regime for coherent one-color PA using an electric-dipole allowed transition is vanishingly small, but this is not the case when exciting to a long-lived molecular state such as found on a metastable triplet potential in an alkaline-earth-metal atom.…”

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Rabi Oscillations between Atomic and Molecular Condensates Driven with Coherent One-Color Photoassociation

et al. 2013

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We demonstrate coherent one-color photoassociation of a Bose-Einstein condensate, which results in Rabi oscillations between atomic and molecular condensates. We attain atom-molecule Rabi frequencies that are comparable to decoherence rates by driving photoassociation of atoms in an 88 Sr condensate to a weakly bound level of the metastable 1 S0+ 3 P1 molecular potential, which has a long lifetime and a large Franck-Condon overlap integral with the ground scattering state. Transient shifts and broadenings of the excitation spectrum are clearly seen at short times, and they create an asymmetric excitation profile that only displays Rabi oscillations for blue detuning from resonance.Coherent conversion of atoms into molecules in quantum degenerate gases provides a path to create molecular condensates, and it is also of fundamental interest because of the complex dynamics of many-body systems with nonlinear couplings [1]. It has been demonstrated with magnetic-field ramps near a magnetic Feshbach resonance (MFR) [2,3] and with different configurations of two-color photoassociation (PA) [4][5][6][7]. Coherent onecolor PA has typically been considered inaccessible due to the short lifetime of excited molecular states in alkalimetal atoms [8]. In addition, the observation of giant Rabi oscillations between atomic and molecular condensates has remained elusive, although it has been discussed extensively since the earliest days of the study of quantum gases [8][9][10][11][12][13][14][15][16][17][18][19]. Here, we demonstrate coherent, one-color PA and Rabi oscillations between atomic and molecular condensates. We also observe transient shifts and broadenings of the excitation spectra at short times and indications of universal dynamics on resonance [8], all of which have not been experimentally studied previously. We access the coherent regime by photoassociating atoms in an 88 Sr condensate [20] to a weakly bound level of the metastable 1 S 0 + 3 P 1 molecular potential. This yields a long molecular lifetime and a large Franck-Condon overlap integral between ground and excited states, which allows atom-molecule coupling to exceed loss and decoherence rates. [6,28]. These two-color processes are typically coherent, as demonstrated, for example, by the suppression of PA loss [4]. Rabi oscillations between atomic and ground molecular condensates driven by twocolor PA [12,[14][15][16] have never been observed, even in optical lattices [5], although two-photon Raman coupling was recently used to observe Rabi oscillations in a degenerate Fermi gas [29]. Spontaneous Raman scattering by molecules presents a formidable challenge to accessing a regime in which the two-photon coupling exceeds the decoherence rate [5].Coherence seems even less accessible in one-color PA because of the short lifetime of excited molecular states. Simply increasing the laser intensity and atom-molecule Rabi frequency does not necessarily offer a solution because transfer of population to noncondensate atomic states becomes dominant at high laser cou...

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Rabi Oscillations between Atomic and Molecular Condensates Driven with Coherent One-Color Photoassociation

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“…The experimental signal exhibits a distinct step at zero delay: the signal is greater for a pump-probe sequential pulse order. The peak near zero delay corresponds to dipole transient effects previously reported [5]. Fourier analysis of the subsequent positive-delay signal does not reveal any dominant characteristic oscillatory periods.…”

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A pump-probe study of the photoassociation of cold rubidium molecules

McCabe

England

Martay

et al. 2009

CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference

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“…This behavior is not expected for a vibrational wave-packet oscillating in an anharmonic molecular potential. The observed oscillatory dynamics are instead due to so-called coherent transients [22,23], which is a coherent energy exchange between molecules and the pump-pulse laser field. A detailed discussion of this is given in our accompanying theoretical paper [24].…”

Section: Femtosecond Photoassociationmentioning

confidence: 99%

“…In the current paper we give a detailed description of the experiment and present the analysis of the results of Ref. [23]. The comparison with the theoretical description will be presented in our subsequent article [24].…”

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confidence: 99%

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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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Coherent Transients in the Femtosecond Photoassociation of Ultracold Molecules

Cited by 59 publications

References 22 publications

Rabi Oscillations between Atomic and Molecular Condensates Driven with Coherent One-Color Photoassociation

Rabi Oscillations between Atomic and Molecular Condensates Driven with Coherent One-Color Photoassociation

A pump-probe study of the photoassociation of cold rubidium molecules

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

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