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- Dion, Claude, 1970-, et al.
(författare)
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Bimodal momentum distribution of laser-cooled atoms in optical lattices
- 2016
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 93:5
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Tidskriftsartikel (refereegranskat)abstract
- We study, numerically and experimentally, the momentum distribution of atoms cooled in optical lattices. Using semiclassical simulations, we show that this distribution is bimodal, made up of a central feature corresponding to "cold," trapped atoms, with tails of "hot," untrapped atoms, and that this holds true also for very shallow potentials. Careful analysis of the distribution of high-momentum untrapped atoms, both from simulations and experiments, shows that the tails of the distribution do not follow a normal law, hinting at a power-law distribution and nonergodic behavior. We also revisit the phenomenon leading to the existence of an optimal cooling point, i.e., a potential depth below which the temperature of the atoms starts increasing.
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- Dion, Claude, et al.
(författare)
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Controllable 3D atomic Brownian motor in optical lattices
- 2008
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Ingår i: The European Physical Journal - Special Topics. - : Springer Science and Business Media LLC. - 1951-6355 .- 1951-6401. ; 159:1, s. 11-17
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Tidskriftsartikel (refereegranskat)abstract
- We study a Brownian motor, based on cold atoms in optical lattices, where atomic motion can be induced in a controlled manner in an arbitrary direction, by rectification of isotropic random fluctuations. In contrast with ratchet mechanisms, our Brownian motor operates in a potential that is spatially and temporally symmetric, in apparent contradiction to the Curie principle. Simulations, based on the Fokker-Planck equation, allow us to gain knowledge on the qualitative behaviour of our Brownian motor. Studies of Brownian motors, and in particular ones with unique control properties, are of fundamental interest because of the role they play in protein motors and their potential applications in nanotechnology. In particular, our system opens the way to the study of quantum Brownian motors.
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- Dion, Claude M., et al.
(författare)
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Time dependence of laser cooling in optical lattices
- 2005
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Ingår i: Europhysics letters. - Les Ulis : Éditions de physique. - 0295-5075 .- 1286-4854. ; 72:3, s. 369-375
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Tidskriftsartikel (refereegranskat)abstract
- We study the dynamics of the cooling of a gas of caesium atoms in an optical lattice, both experimentally and with 1D full-quantum Monte Carlo simulations. We find that, contrary to the standard interpretation of the Sisyphus model, the cooling process does not work by a continuous decrease of the average kinetic energy of the atoms in the lattice. Instead, we show that the momentum of the atoms follows a bimodal distribution, the atoms being gradually transferred from a hot to a cold mode. We suggest that the cooling mechanism should be depicted in terms of a rate model, describing the transfer between the two modes along with the processes occurring within each mode.
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- Froelich, Piotr, et al.
(författare)
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Antihydrogen in Interaction with Atoms and Surfaces
- 2005
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Ingår i: AIP Conference Proceedings. - : AIP. - 0094-243X .- 1551-7616. ; 770:1, s. 51-67, s. 51-67
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Anoverview of the antiatom interactions with matter is given inthe context of the ongoing efforts to trap and coolantihydrogen at CERN. We show how the atom-antiatom scattering can,in addition to annihilation, result in a number of collisionalreactions such as elastic scattering, rearrangement to protonium and positronium,and even radiative association leading to formation of unusual short-livedatom-antiatom molecules. We also show that sufficiently cold antiatoms canbe reflected from material walls. The rates for these reactionsare of interest for the experiments with antihydrogen atoms atCERN, they probe the feasibility of collisional cooling of antihydrogenand they contribute to the understanding of stability of matterin contact with antimatter in general.
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