Optimizing the efficiency of evaporative cooling in optical dipole traps

Olson, Abraham; Niffenegger, Robert; Chen, Yong P.

doi:10.1103/physreva.87.053613

Cited by 36 publications

(41 citation statements)

References 29 publications

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“…Because the wavelength of the ODT is close to the 5P 3/2 -4D transitions of Rb 87 (1529 nm), the ac-Stark shift of the excited state 5P 3/2 is much stronger than that of the ground state 5S 1/2 , as first reported by [33][34][35]. The ratio of these light-shifts is about 47, corresponding to the ratio of the scalar polarizabilities of the excited state and ground state.…”

Section: Apparatus and State Preparationmentioning

confidence: 55%

Multi-second magnetic coherence in a single domain spinor Bose–Einstein condensate

et al. 2018

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We describe a compact, robust and versatile system for studying the macroscopic spin dynamics in a spinor Bose-Einstein condensate. Condensates of Rb 87 are produced by all-optical evaporation in a 1560 nm optical dipole trap, using a non-standard loading sequence that employs an ancillary 1529 nm beam for partial compensation of the strong differential light-shift induced by the dipole trap itself. We use near-resonant Faraday rotation probing to non-destructively track the condensate magnetization, and demonstrate few-Larmor-cycle tracking with no detectable degradation of the spin polarization. In the ferromagnetic F=1 ground state, we observe the spin orientation between atoms in the condensate is preserved, such that they precess all together like one large spin in the presence of a magnetic field. We characterize this dynamics in terms of the single-shot magnetic coherence times 1  and 2 *  , and observe them to be of several seconds, limited only by the residence time of the atoms in the trap. At the densities used, this residence is restricted only by one-body losses set by the vacuum conditions.

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Section: Apparatus and State Preparationmentioning

confidence: 55%

Multi-second magnetic coherence in a single domain spinor Bose–Einstein condensate

et al. 2018

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“…For our experiment, we produce nearly-pure 3D BECs of 1 − 2 × 10 4 87 Rb atoms in an optical dipole trap [23], with trapping frequencies tuned in the range of ω z,y /2π ≈ 180-450 Hz and ω x /2π ≈ 50-90 Hz. To create synthetic spin-orbit coupling, we employ counterpropagating Raman beams along theŷ-axis which couple the |m F states of the F = 1 ground state manifold of 87 Rb (see Fig.…”

Section: Methodsmentioning

confidence: 99%

Tunable Landau-Zener transitions in a spin-orbit-coupled Bose-Einstein condensate

et al. 2014

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The Landau-Zener (LZ) transition is one of the most fundamental phenomena in quantum dynamics. It describes nonadiabatic transitions between quantum states near an avoided crossing that can occur in diverse physical systems. Here we report experimental measurements and tuning of LZ transitions between the dressed eigenlevels of a synthetically spin-orbit (SO) coupled Bose-Einstein condensate (BEC). We measure the transition probability as the BEC is accelerated through the SO avoided crossing, and study its dependence on the coupling between the diabatic (bare) states, eigenlevel slope, and eigenstate velocity-the three parameters of the LZ model that are independently controlled in our experiments. Furthermore, we performed time-resolved measurements to demonstrate the breaking-down of the spin-momentum locking of the spin-orbit coupled BEC in the nonadiabatic regime, and determine the diabatic switching time of the LZ transitions. Our observations show quantitative agreement with the LZ model and numerical simulations of the quantum dynamics in the quasimomentum space. The tunable LZ transition may be exploited to enable a spin-dependent atomtronic transistor.

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“…The ability to dynamically control the center position modulation (CPM) amplitude of the beam in addition to its total power, results in independent, arbitrary control over both the trap depth (U = ηk B T ) and frequency as a function of time, a key advantage over methods with a fixed power-law relationship between U andω [18,23].…”

Section: Introductionmentioning

confidence: 99%

“…Crucially, unlike in 1-body loss dominated systems, the inverted scaling of R with density means maintaining a large N leads to loweredω, reduced collision rates and longer evaporation timescales. Numerical modeling of evaporative cooling in an ODT [22,23] can help optimize γ, but the challenges of large number and speed remain.…”

Section: Introductionmentioning

confidence: 99%

Rapid cooling to quantum degeneracy in dynamically shaped atom traps

et al. 2016

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We report on a general method for the rapid production of quantum degenerate gases. Using 174 Yb, we achieve an experimental cycle time as low as (1.6 − 1.8) s for the production of BoseEinstein condensates (BECs) of (0.5−1)×10 5 atoms. While laser cooling to 30 µK proceeds in a standard way, evaporative cooling is highly optimized by performing it in an optical trap that is dynamically shaped by utilizing the time-averaged potential of a single laser beam moving rapidly in one dimension. We also produce large (> 10 6 ) atom number BECs and successfully model the evaporation dynamics over more than three orders of magnitude in phase space density. Our method provides a simple and general approach to solving the problem of long production times of quantum degenerate gases.

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Optimizing the efficiency of evaporative cooling in optical dipole traps

Cited by 36 publications

References 29 publications

Multi-second magnetic coherence in a single domain spinor Bose–Einstein condensate

Multi-second magnetic coherence in a single domain spinor Bose–Einstein condensate

Tunable Landau-Zener transitions in a spin-orbit-coupled Bose-Einstein condensate

Rapid cooling to quantum degeneracy in dynamically shaped atom traps

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