A high flux source of cold strontium atoms

We report on the realization of a transversely loaded two-dimensional magneto-optical trap serving as a source for cold strontium atoms. We analyze the dependence of the source's properties on various parameters, in particular the intensity of a pushing beam accelerating the atoms out of the source. An atomic flux exceeding 10 9 atoms/s at a rather moderate oven temperature of 500• C is achieved. The longitudinal velocity of the atomic beam can be tuned over several tens of m/s by adjusting the power of the pushing laser beam. The beam divergence is around 60 mrad, determined by the transverse velocity distribution of the cold atoms. The slow atom source is used to load a threedimensional magneto-optical trap realizing loading rates up to 10 9 atoms/s without indication of saturation of the loading rate for increasing oven temperature. The compact setup avoids undesired effects found in alternative sources like, e.g., Zeeman slowers, such as vacuum contamination and black-body radiation due to the hot strontium oven.

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“…The corresponding loading rates would then be comparable to those of most reported strontium 3D-MOTs using Zeeman slowers [49][50][51].…”

Section: Discussionsupporting

confidence: 75%

Two-dimensional magneto-optical trap as a source for cold strontium atoms

Nosske

Couturier

et al. 2017

Phys. Rev. A

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“…In brief, this source is composed of an oven similar to [46], followed by a transverse cooling stage and a Zeeman slower, both using laser cooling on the broad-linewidth blue transition. A 2D blue MOT [47][48][49], whose non-confining axis is oriented in the direction of gravity, is located approximately 5 cm after the exit of the Zeeman slower (see Figure 1a). This MOT has a loading rate of 2.66(16) × 10 9 88 Sr atoms/s (measured by absorption imaging) and cools atoms to about 1 mK in the radial (xz) plane.…”

mentioning

confidence: 99%

Steady-State Magneto-Optical Trap with 100-Fold Improved Phase-Space Density

et al. 2017

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We demonstrate a continuously loaded 88 Sr magneto-optical trap (MOT) with a steady-state phase-space density of 1.3(2) × 10 −3 . This is two orders of magnitude higher than reported in previous steady-state MOTs. Our approach is to flow atoms through a series of spatially separated laser cooling stages before capturing them in a MOT operated on the 7.4-kHz linewidth Sr intercombination line using a hybrid slower+MOT configuration. We also demonstrate producing a Bose-Einstein condensate at the MOT location, despite the presence of laser cooling light on resonance with the 30-MHz linewidth transition used to initially slow atoms in a separate chamber. Our steady-state high phase-space density MOT is an excellent starting point for a continuous atom laser and dead-time free atom interferometers or clocks.Laser cooled and trapped atoms are at the core of most ultracold quantum gas experiments [1], state-ofthe-art clocks [2] and sensors based on atom interferometry [3]. Today, these devices typically operate in a time-sequential manner, with distinct phases for sample preparation and measurement. For atomic clocks a consequence is the need to bridge the dead time between measurements using a secondary frequency reference, typically a resonator. This introduces a problem known as the Dick effect [4] in which the sampling process inherent to a clock's cyclic operation down converts or aliases high frequency noise from the secondary reference into the signal band, thus degrading performance [5]. Recently, a new generation of atomic clocks using degenerate atoms in a three-dimensional optical lattice has been demonstrated using Sr [6]. To reach the potential of such a clock, it will be necessary to overcome the Dick effect, which can be achieved by reducing the dead time and/or by creating vastly improved secondary references. Our steady-state MOT can lead to significant advances in both directions. It approaches the high flux and low temperature requirements needed for a steadystate clock, which would completely eliminate the Dick effect. Furthermore, our MOT is created under conditions compatible with the creation of degenerate samples or an atom laser [7,8]. This would be the ideal source for a secondary frequency reference based on superradiant lasing, which is expected to outperform current references [9][10][11][12][13]. Our source and a future atom laser based on it might also be valuable for atomic inertial sensors [8]. Improved clocks and inertial sensors will allow tests of fundamental physics [14] or be suitable for gravitational wave astronomy [3,[15][16][17].Over the years many creative approaches have honed laser cooling to produce pulsed samples of ever increasing phase-space density (PSD) [18][19][20][21][22][23][24][25][26][27][28][29]. Pulsed MOTs using 88 Sr have demonstrated phase-space densities of 10 −2 [30] while atoms held in dipole traps recently reached degeneracy [7,31]. Despite the exquisite performances, these techniques suffer from extremely small capture velocities.As a consequence atoms ...

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“…Compared to other Sr atomic sources, our sidebandenhanced 2D-MOT source shows high transfer efficiency L SB MOT /Φ SB = 48(8)%, with a MOT loading rate slightly larger than a ZS-enhanced Sr 2D-MOT source [18], and less than a factor ten lower than more complex and power-demanding high-flux source systems based, for instance, on a combination of Zeeamn slower, 2D-MOT and deflection [37].…”

Section: A Loading a Mot With Sideband-enhancementmentioning

confidence: 97%

Sideband-Enhanced Cold Atomic Source for Optical Clocks

et al. 2020

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We demonstrate the enhancement and optimization of a cold strontium atomic beam from a twodimensional magneto-optical trap (2D-MOT) transversely loaded from a collimated atomic beam by adding a sideband frequency to the cooling laser. The parameters of the cooling and sideband beams were scanned to achieve the maximum atomic beam flux and compared with Monte Carlo simulations. We obtained a 2.3 times larger, and 4 times brighter, atomic flux than a conventional, single-frequency 2D-MOT, for a given total power of 200 mW. We show that the sideband-enhanced 2D-MOT can reach the loading rate performances of space demanding Zeeman slower-based systems, while it can overcome systematic effects due to thermal beam collisions and hot black-body radiation shift, making it suitable for both transportable and accurate optical lattice clocks. Finally we numerically studied the possible extensions of the sideband-enhanced 2D-MOT to other alkalineearth species.A 2D-MOT atomic source relies on the radiationpressure friction force to capture and cool thermal atoms effusing from either an oven, or a background gas. In this work, we focus our attention on the 2D-MOT loaded from a collimated atomic source, so that a 1D model of-arXiv:1909.05810v1 [physics.atom-ph]

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A high flux source of cold strontium atoms

Cited by 50 publications

References 48 publications

Two-dimensional magneto-optical trap as a source for cold strontium atoms

Two-dimensional magneto-optical trap as a source for cold strontium atoms

Steady-State Magneto-Optical Trap with 100-Fold Improved Phase-Space Density

Sideband-Enhanced Cold Atomic Source for Optical Clocks

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