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We report recent progress on the development of magnetic mirrors for reflecting beams of slowly moving neutral atoms. Different approaches for constructing periodic magnetic structures with micron-scale periodicities are described...
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We report recent progress on the development of magnetic mirrors for reflecting beams of slowly moving neutral atoms. Different approaches for constructing periodic magnetic structures with micron-scale periodicities are described, including the use of arrays of current-carrying wires fabricated by photolithography, grooved ferromagnetic structures fabricated by electron-beam lithography, and magnetic structures recorded on magneto-optical film by a focused diode laser beam, Results on the reflection of free-falling laser-cooled caesium atoms from these microfabricated magnetic mirrors are presented.
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We propose a novel generic approach to laser cooling based on the nonresonant interactions of atoms and molecules with optical standing waves experiencing sudden phase jumps. The technique, termed "optical shaking," combines the e...
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We propose a novel generic approach to laser cooling based on the nonresonant interactions of atoms and molecules with optical standing waves experiencing sudden phase jumps. The technique, termed "optical shaking," combines the elements of stochastic cooling and Sisyphus cooling. An optical signal that measures the instantaneous force applied by the standing wave on the ensemble of particles is used as feedback to determine the phase jumps. This guarantees a drift towards lower energies and higher phase-space density without the loss of particles typical of evaporative cooling.
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We show how to construct asymmetric optical barriers for atoms. These barriers can be used to compress phase-space of a sample by creating a confined region in space where atoms can accumulate with heating at the single photon rec...
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We show how to construct asymmetric optical barriers for atoms. These barriers can be used to compress phase-space of a sample by creating a confined region in space where atoms can accumulate with heating at the single photon recoil level. We illustrate our method with a simple two-level model and then show how it can be applied to more realistic multilevel atoms.
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This article presents a new experiment aiming at BEC of metastable helium atoms. It describes the design of a high flux discharge source of atoms and a robust laser system using a DBR diode coupled with a high power Yb doped fiber...
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This article presents a new experiment aiming at BEC of metastable helium atoms. It describes the design of a high flux discharge source of atoms and a robust laser system using a DBR diode coupled with a high power Yb doped fiber amplifier for manipulating the beam of metastable atoms. The atoms are trapped in a small quartz cell in an extreme high vacuum. The trapping design uses an additional laser (repumper) and allows the capture of a large number of metastable helium atoms (approximately 10~9) in a geometry favorable for loading a tight magnetostatic trap.
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We present a direct measurement of velocity distributions in two dimensions by using an absorption imaging technique in a 3D near resonant optical lattice. The results show a clear difference in the velocity distributions for the ...
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We present a direct measurement of velocity distributions in two dimensions by using an absorption imaging technique in a 3D near resonant optical lattice. The results show a clear difference in the velocity distributions for the different directions. The experimental results are compared with a numerical 3D semi-classical Monte-Carlo simulation. The numerical simulations are in good qualitative agreement with the experimental results.
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A variable length linear trap operating between 20-1000 Hz under standard temperature and pressure conditions is reported. We simulated and observed various kinds of stable patterns: linear strings, planar zig-zag and volume struc...
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A variable length linear trap operating between 20-1000 Hz under standard temperature and pressure conditions is reported. We simulated and observed various kinds of stable patterns: linear strings, planar zig-zag and volume structures. The interparticle distances depend on the trapped particle number and trap length. Our setup allows trapped microparticle diagnosis by various methods.
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We report on a novel mechanism that allows for strong laser cooling of atoms that do not have a closed cycling transition. This mechanism is observed in a magneto-optical trap (MOT) for erbium, an atom with a very complex energy l...
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We report on a novel mechanism that allows for strong laser cooling of atoms that do not have a closed cycling transition. This mechanism is observed in a magneto-optical trap (MOT) for erbium, an atom with a very complex energy level structure with multiple pathways for optical-pumping losses. We observe surprisingly high trap populations of over 10~6 atoms and densities of over 10~(11) atoms cm~(-3), despite the many potential loss channels. A model based on recycling of metastable and ground state atoms held in the quadrupole magnetic field of the trap explains the high trap population, and agrees well with time-dependent measurements of MOT fluorescence. The demonstration of trapping of a rare-earth atom such as erbium opens a wide range of new possibilities for practical applications and fundamental studies with cold atoms.
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There are interesting modifications to the Doppler force when atoms strongly couple to an optical cavity. In particular, there is the possibility to increase the velocity capture range while maintaining a final temperature close t...
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There are interesting modifications to the Doppler force when atoms strongly couple to an optical cavity. In particular, there is the possibility to increase the velocity capture range while maintaining a final temperature close to the Doppler limit. The mechanism is based on the multiple absorption emissions of each cavity photon. A previously reported counterintuitive Doppler effect is clarified.
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We report the use of photoassociative spectroscopy to determine the ground-state .s-wave scattering lengths for the main bosonic isotopes of strontium, ~(86)Sr and ~(88)Sr. Photoassociative transitions are driven with a laser red ...
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We report the use of photoassociative spectroscopy to determine the ground-state .s-wave scattering lengths for the main bosonic isotopes of strontium, ~(86)Sr and ~(88)Sr. Photoassociative transitions are driven with a laser red detuned by up to 1400 GHz from the ~1S_0-~1P_1 atomic resonance at 461 nm. A minimum in the transition amplitude for ~(86)Sr at -494 ± 5 GHz allows us to determine the scattering lengths 610a_0 < a_(86) < 2300a_0 for ~(86)Sr and a much smaller value of -1a_0 < a_(88) < 13a_0 for ~(88)Sr.
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We report photoassociative spectroscopy of ~(88)Sr_2 in a magneto-optical trap operating on the ~1S_0 →~3P_1 intercombination line at 689 nm. Photoassociative transitions are driven with a laser red detuned by 600-2400 MHz from t...
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We report photoassociative spectroscopy of ~(88)Sr_2 in a magneto-optical trap operating on the ~1S_0 →~3P_1 intercombination line at 689 nm. Photoassociative transitions are driven with a laser red detuned by 600-2400 MHz from the ~1S_0 → ~1P_1 atomic resonance at 461 nm. Photoassociation takes place at extremely large internuclear separation, and the photoassociative spectrum is strongly affected by relativistic retardation. A fit of the transition frequencies determines the ~1P_1 atomic lifetime (τ = 5.22 ± 0.03 ns) and resolves a discrepancy between experiment and recent theoretical calculations.
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