Collisions of dressed ground-state atoms

Moerdijk, A. J.; Verhaar, B.J.; Nagtegaal, T.M.

doi:10.1103/physreva.53.4343

Cited by 55 publications

(54 citation statements)

References 27 publications

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“…With the large coupling strength and gradients obtainable on atom chips, the formation of RF and MW induced Feshbach resonances [24] become feasible.…”

Section: Discussionmentioning

confidence: 99%

“…Nevertheless we observe no additional loss for atoms trapped in RF potentials compared to the static trap for densities up to 10 15 atoms/cm 3 . We attribute this collisional stability of atoms in the RF dressed states to an argument given in [23,24] for weakly dressed atoms during RF-evaporation in magnetic traps: The RF-fields introduce a variation of the potential on length scales smaller than the original static trap, but still large compared to the scattering length of the atoms. Two colliding atom reside in the same adiabatic state, consequently they can be regarded to be in the same spin state when they approach each other closely.…”

Section: Collisional Stabilitymentioning

confidence: 99%

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Radiofrequency-dressed-state potentials for neutral atoms

et al. 2006

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Potentials for atoms can be created by external fields acting on properties like magnetic moment, charge, polarizability, or by oscillating fields which couple internal states. The most prominent realization of the latter is the optical dipole potential formed by coupling ground and electronically excited states of an atom with light. Here we present an experimental investigation of the remarkable properties of potentials derived from radio-frequency (RF) coupling between electronic ground states. The coupling is magnetic and the vector character allows to design state dependent potential landscapes. On atom chips this enables robust coherent atom manipulation on much smaller spatial scales than possible with static fields alone. We find no additional heating or collisional loss up to densities approaching 10 15 atoms / cm 3 compared to static magnetic traps. We demonstrate the creation of Bose-Einstein condensates in RF potentials and investigate the difference in the interference between two independently created and two coherently split condensates in identical traps. All together this makes RF dressing a powerful new tool for micro manipulation of atomic and molecular systems. Dressing of internal states of an atom with an external field is a well known technique in quantum optics [1]. The coupling of atomic states to an oscillating field leads to new eigenstates and eigenenergies in the combined system. These dressed states can form adiabatic potentials, which can be employed for atom trapping and manipulation. The most prominent example is the optical dipole potential [2] created when intense coherent light couples ground and electronically excited states of an atom. To create conservative potentials for coherent manipulation spontaneous relaxation of the excited state has to be avoided and hence the light field has to be far detuned. Consequently the magnitude and shape of the dipole potential is given by the local intensity of the light field. Such far detuned dipole potentials are widely used in ultra cold atom experiments [3].Dressing can also be achieved by coupling hyperfine components of the electronic ground state by a magnetic radio-frequency (RF) or micro-wave (MW) field. Dressed state potentials resulting from RF coupling of two spin states in a magnetic field have been studied in neutron optics [4]. Adiabatic potentials induced by coupling hyperfine states with a micro wave have been proposed in Ref. [5], and a detuned micro-wave has been used for trapping ultra cold Cs atoms [6]. The trapping of neutral atoms with RF induced potentials was proposed in [7] and first demonstrated for thermal Rb atoms [8]. Recently RF dressed state potentials were employed for coherent splitting of a one-dimensional Bose-Einstein condensate and matter-wave interference [9]. In this paper, we give for the first time a full experimental demonstra- * Electronic address: hofferberth@atomchip.org tion and analysis of the remarkable properties of these adiabatic RF dressed state potentials, which make them a versatile ...

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“…With the large coupling strength and gradients obtainable on atom chips, the formation of RF and MW induced Feshbach resonances [24] become feasible.…”

Section: Discussionmentioning

confidence: 99%

Section: Collisional Stabilitymentioning

confidence: 99%

Radiofrequency-dressed-state potentials for neutral atoms

et al. 2006

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“…This sudden increase of the inelastic transition rates can be reproduced semiquantitatively by applying the distorted wave Born approximation (DWBA) [22], as has been successfully done for the magnetic dipolar interaction of cold alkali atoms [10,11] as well as in a number of problems in cold collisions [25,26]. The first order DWBA is a simple two state perturbation approximation applicable in cases where inelastic scattering is weak in comparison with elastic scattering.…”

Section: A Magnetic Field Dependencementioning

confidence: 99%

“…Studies of spin-changing ultracold collisions in the presence of an external magnetic field have been performed so far only for atomic species [10][11][12]. In this paper, we present a detailed dynamical study at cold and ultracold temperatures for the atom-diatom system 17 O 2 − 3 He in a field.…”

Section: Introductionmentioning

confidence: 99%

Magnetic-field effects in ultracold molecular collisions

Volpi

Bohn

2002

Phys. Rev. A

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We investigate the collisional stability of magnetically trapped ultracold molecules, taking into account the influence of magnetic fields. We compute elastic and spin-state-changing inelastic rate constants for collisions of the prototype molecule 17 O 2 with a 3 He buffer gas as a function of the magnetic field and the translational collision energy. We find that spin-state-changing collisions are suppressed by Wigner's threshold laws as long as the asymptotic Zeeman splitting between incident and final states does not exceed the height of the centrifugal barrier in the exit channel. In addition, we propose a useful one-parameter fitting formula that describes the threshold behavior of the inelastic rates as a function of the field and collision energy. Results show a semi-quantitative agreement of this formula with the full quantum calculations, and suggest useful applications also to different systems. As an example, we predict the low-energy rate constants relevant to evaporative cooling of molecular oxygen.

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“…Rather than finesse the experiments to lower the temperature of the gas further, a more fruitful approach might be to adjust the atom-atom interaction so as to raise the value of the critical temperature. Possible means for adjustment include the magnetic-field-induced Feshbach resonance [5], rf microwave fields [6], dc electric fields [7], and photoassociation [8,9]. In fact, the Feshbach resonance has been recently applied in this manner to induce condensation in the otherwise incondensable 85 Rb [10], and was additionally explored (theoretically) for its usefulness in spurring the superfluid transition [11].…”

mentioning

confidence: 99%

Driving superfluidity with photoassociation

Mackie¹,

Timmermans²,

Côté³

et al. 2001

Opt. Express

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We theoretically examine photoassociation of a two-component Fermi degenerate gas. Our focus is on adjusting the atom-atom interaction, and thereby increaing the critical temperature of the BCS transition to the superfluid state. In order to avoid spontaneous decay of the molecules, the photoassociating light must be far-off resonance. Very high light intensities are therefore required for effective control of the BCS transition.Typeset using REVT E X 1

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Collisions of dressed ground-state atoms

Cited by 55 publications

References 27 publications

Radiofrequency-dressed-state potentials for neutral atoms

Radiofrequency-dressed-state potentials for neutral atoms

Magnetic-field effects in ultracold molecular collisions

Driving superfluidity with photoassociation

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