Production of quantum-degenerate strontium gases

Stellmer, Simon; Grimm, Rudolf; Schreck, Florian

doi:10.1103/physreva.87.013611

Cited by 113 publications

(147 citation statements)

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“…The trap frequencies in this configuration are (ν x , ν y , ν z ) = (509, 447, 262) Hz. Our minimum temperature is comparable to the lowest ones achieved with sympathetic cooling schemes based on s-wave scattering [24][25][26]. While the crucial role of the long-range character of the dipole-dipole interaction (DDI) clearly emerges in the evaporation of spin-polarized fermions, the role of the anisotropy of the interaction is more subtle.…”

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confidence: 51%

Anisotropic Relaxation Dynamics in a Dipolar Fermi Gas Driven Out of Equilibrium

et al. 2014

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We report on the observation of a large anisotropy in the rethermalization dynamics of an ultracold dipolar Fermi gas driven out of equilibrium. Our system consists of an ultracold sample of strongly magnetic 167 Er fermions, spin-polarized in the lowest Zeeman sublevel. In this system, elastic collisions arise purely from universal dipolar scattering. Based on cross-dimensional rethermalization experiments, we observe a strong anisotropy of the scattering, which manifests itself in a large angular dependence of the thermal relaxation dynamics. Our result is in good agreement with recent theoretical predictions. Furthermore, we measure the rethermalization rate as a function of temperature for different angles and find that the suppression of collisions by Pauli blocking is not influenced by the dipole orientation.PACS numbers: 03.75. Ss, 37.10.De, 51.60.+a, 67.85.Lm The behavior of any many-body system follows from the interactions of its constituent particles. In some cases of physical interest, importantly at ultralow temperature, where the de Broglie wavelength is the dominant length scale, these interactions can be simplified by appealing to the Wigner threshold laws [1,2]. These laws, which have been extensively studied for particles interacting via van der Waals forces, both in experiment and theory [3], identify the interactions via simple isotropic parameters such as a scattering length. However, for dipolar particles, the fundamental interaction is anisotropic and the system properties can depend on the orientation of the gas with respect to a particular direction in space. [4,5].One of the major strengths of ultracold matter is its susceptibility to being controlled by various means. Striking examples include traversing the BEC-BES crossover [6,7], welding atoms together into molecules [8,9], and inducing bosons to behave like fermions in one spatial dimension [10,11]. Most often, such control exploits the quantum mechanical nature of a many-body gas at ultralow temperature, and arises from the manipulation of isotropic scattering between constituent particles. However, in the case of dipolar particles the scattering is intrinsically anisotropic, affording novel opportunities to control the behavior of the gas. For example, the anisotropic d-wave collapse of a Bose-Einstein condensate of magnetic atoms [12,13] and the deformation of the Fermi sphere in a dipolar Fermi gas [14] have been observed. These phenomena rely on the collective behavior of all the particles, occurring according to their mean field energy.Distinct from such many-body effects, dipoles can also influence the properties of the gas via two-body scattering. Since scattering of dipoles is highly anisotropic, properties that require the collisional exchange of energy and momentum between the atoms, such as sound propagation, viscosity, and virial coefficients [15], will be influenced by the presence of dipoles. In particular, differential cross sections of dipolar particles are highly anisotropic, depending on both the initial, as ...

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confidence: 51%

Anisotropic Relaxation Dynamics in a Dipolar Fermi Gas Driven Out of Equilibrium

et al. 2014

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“…This was achieved by reducing the density in a large volume optical dipole trap [76,77]. Furthremore, a BEC of 88 Sr was produced by the Rice group, which used sympathetic cooling with 87 Sr [78].…”

Section: Strontiummentioning

confidence: 99%

Ultracold Fermi gases with emergent SU(N) symmetry

2014

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We review recent experimental and theoretical progress on ultracold alkaline-earth Fermi gases with emergent SU(N ) symmetry. Emphasis is placed on describing the ground-breaking experimental achievements of recent years. The latter include the cooling to below quantum degeneracy of various isotopes of ytterbium and strontium, the demonstration of optical Feshbach resonances and the optical Stern-Gerlach effect, the realization of a Mott insulator of 173 Yb atoms, the creation of various kinds of Fermi-Bose mixtures and the observation of many-body physics in optical lattice clocks. On the theory side, we survey the zoo of phases that have been predicted for both gases in a trap and loaded into an optical lattice, focusing on two and three-dimensional systems. We also discuss some of the challenges that lie ahead for the realization of such phases, such as reaching the temperature scale required to observe magnetic and more exotic quantum orders, and dealing with collisional relaxation of excited electronic levels.

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“…The experimental apparatus is our Sr quantum gas machine, which is described in depth in [29]. The experimental sequence leading to a Bose-Einstein condensate (BEC) of 84 Sr starts with a magneto-optical trap operating on the 1 S 0 − 1 P 1 transition, capturing atoms coming from a Zeeman slower.…”

Section: Experimental Setup and Creation Of The Mott Insulatormentioning

confidence: 99%

Efficient production of long-lived ultracold Sr2 molecules

et al. 2017

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We associate Sr atom pairs on sites of a Mott insulator optically and coherently into weaklybound ground-state molecules, achieving an efficiency above 80%. This efficiency is 2.5 times higher than in our previous work [S. Stellmer, B. Pasquiou, R. Grimm, and F. Schreck, Phys. Rev. Lett. 109, 115302 (2012)] and obtained through two improvements. First, the lifetime of the molecules is increased beyond one minute by using an optical lattice wavelength that is further detuned from molecular transitions. Second, we compensate undesired dynamic light shifts that occur during the stimulated Raman adiabatic passage (STIRAP) used for molecule association. We also characterize and model STIRAP, providing insights into its limitations. Our work shows that significant molecule association efficiencies can be achieved even for atomic species or mixtures that lack Feshbach resonances suitable for magnetoassociation.

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Production of quantum-degenerate strontium gases

Cited by 113 publications

References 113 publications

Anisotropic Relaxation Dynamics in a Dipolar Fermi Gas Driven Out of Equilibrium

Anisotropic Relaxation Dynamics in a Dipolar Fermi Gas Driven Out of Equilibrium

Ultracold Fermi gases with emergent SU(N) symmetry

Efficient production of long-lived ultracold Sr2 molecules

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