Time dependence of laser cooling in optical lattices

Dion, Claude M.; Sjölund, Peder; Petra, S.J.H.; Jonsell, Svante; Kastberg, Anders

doi:10.1209/epl/i2005-10244-6

Cited by 8 publications

(18 citation statements)

References 33 publications

(52 reference statements)

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“…2, reflects the fact that it is the laser irradiance, and not strictly the potential depth, that is modified. In addition, the current experiment probes a region corresponding to a low-mobility locked state, in accord with the fact that most atoms have an energy below the well-to-well barrier height [27,31]. Note that the semi-classical model used here cannot reproduce the Doppler cooling [20,21] that will become important as the velocity of the atoms increases.…”

Section: Running and Locked Statesmentioning

confidence: 51%

“…The details of the mechanisms for the continued route to equilibrium, for an atom localized in a well, are not precisely known. However, with strong support from experimental and theoretical investigations (c.f., [22,[24][25][26][27][28][29]), we here assume the following. An atom trapped in a well experiences no direct damping.…”

Section: A Laser Coolingmentioning

confidence: 99%

“…By analyzing the velocity distributions obtained by time-of-flight detection, the fraction of atoms in the running state compared with the total amount of atoms, N run /N tot , can be extracted [19,27,31]. Assuming that the momentum distribution corresponds to a (truncated) Gaussian core of trapped atoms, with wide wings corresponding to untrapped atoms, we can calculate approximate numbers for N run /N tot and by Gaussian fits to the momentum distributions.…”

Section: Running and Locked Statesmentioning

confidence: 99%

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Fluctuation-induced drift in a gravitationally tilted optical lattice

et al. 2010

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Experimental and theoretical studies are made of Brownian particles trapped in a periodic potential, which is very slightly tilted due to gravity. In the presence of fluctuations, these will trigger a measurable average drift along the direction of the tilt. The magnitude of the drift varies with the ratio between the bias force and the trapping potential. This can be closely compared to a theoretical model system, based on a Fokker-Planck-equation formalism. We show that the level of control and measurement precision we have in our system, which is based on cold atoms trapped in a 3D dissipative optical lattice, makes the experimental setup suitable as a testbed for fundamental statistical physics. We simulate the system with a very simplified and general classical model, as well as with an elaborate semi-classical Monte-Carlo simulation. In both cases, we achieve good qualitative agreement with experimental data.

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Section: Running and Locked Statesmentioning

confidence: 51%

Section: A Laser Coolingmentioning

confidence: 99%

Section: Running and Locked Statesmentioning

confidence: 99%

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Fluctuation-induced drift in a gravitationally tilted optical lattice

et al. 2010

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“…2 This has been proven to be an oversimplification. 12,13 The deviations are however small and the true shape depends strongly on a variety of parameters and are not yet fully understood. To be able to study these deviations, an accurate mapping of the velocity distribution is crucial.…”

Section: Introductionmentioning

confidence: 99%

“…This non-Gaussian behavior is of interest, as it can carry information of the nature of the cooling mechanism and of the statistical physics governing the atoms in an optical lattice. 13,14 An accurate detection of the velocity distribution can also be used for, e.g., mapping the motional quantum state of the atoms. 15 The temperature and the number of atoms are also critical parameters when, for instance, a BEC should be realized.…”

Section: Introductionmentioning

confidence: 99%

Assessment of a time-of-flight detection technique for measuring small velocities of cold atoms

Hagman

Sjölund

Petra

et al. 2009

Journal of Applied Physics

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A low noise time-of-flight detection system for laser cooled atoms has been constructed and incrementally optimized. Here, a thorough description of the construction is presented along with an analysis of the capabilities of the system. The quality of the detection ͑the resolution, the reproducibility, the sensitivity, etc.͒ is crucial for, e.g., the ability to see details in the velocity distribution profile, which is of interest for fundamental studies of statistical physics and of the laser cooling processes, and for detection of small initial velocities of an atomic cloud, important, e.g., when studying small drifts induced by Brownian motors and ratchets. We estimate the signal-to-noise ratio of our signal to be better than 1000:1 for a typical single shot, and we discuss the effect of the initial atomic cloud size, the probe size, and the effects of the wave packet spread during the fall time on the measured quantities. We show that the shape of the velocity distribution is well conserved during the mapping done in the detection, i.e., in the convolution with the probe beam, and that velocities as small as a few percent of the single photon recoil velocity can be resolved.

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Bimodal momentum distribution of laser-cooled atoms in optical lattices

et al. 2016

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We study, numerically and experimentally, the momentum distribution of atoms cooled in optical lattices. Using semi-classical 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 does not follow a normal law, hinting at a power-law distribution and non-ergodic behavior. We also revisit the phenomenon of d\'ecrochage, the potential depth below which the temperature of the atoms starts increasing

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Time dependence of laser cooling in optical lattices

Cited by 8 publications

References 33 publications

Fluctuation-induced drift in a gravitationally tilted optical lattice

Fluctuation-induced drift in a gravitationally tilted optical lattice

Assessment of a time-of-flight detection technique for measuring small velocities of cold atoms

Bimodal momentum distribution of laser-cooled atoms in optical lattices

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