Optical Control of Ultracold Collisions in Metastable Xenon

Walhout, M.; Sterr, U.; Orzel, Chad; Hoogerland, M. D.; Rolston, S. L.

doi:10.1103/physrevlett.74.506

Cited by 86 publications

(66 citation statements)

References 13 publications

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“…Since then, numerous investigations, both experimental and theoretical, have been made into the collisional properties of many different homonuclear [2,3,4,5,6,7,8,9,10,11,12,13] and (later) heteronuclear [14,15,16,17,18,19] systems. Collisional studies are in themselves interesting, leading to an in-depth understanding of the various scattering mechanisms present at such low kinetic energies and methods by which we can have some measure of control over elastic and inelastic collisions.…”

Section: Introductionmentioning

confidence: 99%

Heteronuclear ionizing collisions between laser-cooled metastable helium atoms

et al. 2007

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We have investigated cold ionizing heteronuclear collisions in dilute mixtures of metastable (2 3 S1) 3 He and 4 He atoms, extending our previous work on the analogous homonuclear collisions [R. J. W. Stas et al., PRA 73, 032713 (2006)]. A simple theoretical model of such collisions enables us to calculate the heteronuclear ionization rate coefficient, for our quasi-unpolarized gas, in the absence of resonant light (T = 1.2 mK): K (th) 34 = 2.4×10 −10 cm 3 /s. This calculation is supported by a measurement of K34 using magneto-optically trapped mixtures containing about 1×10 8 atoms of each species, K (exp) 34 = 2.5(8)×10 −10 cm 3 /s. Theory and experiment show good agreement.

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Section: Introductionmentioning

confidence: 99%

Heteronuclear ionizing collisions between laser-cooled metastable helium atoms

et al. 2007

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“…Additional motivation for these investigations arises from the fact, that favorable rate coefficients for inelastic but also for elastic collisions are essential for the achievement of quantum degeneracy which for Rg* atoms so far has only been demonstrated for 4 He [5][6][7][8] and 3 He [9]. For unpolarized Rg* samples, two-body loss rate coefficients for PI [10] between β = 6 × 10 −11 cm 3 /s for 132 Xe [11] and β = 1 × 10 −9 cm 3 /s for 22 Ne [12] have been measured. Spin polarizing the atoms to a spin-stretched * gerhard.birkl@physik.tu-darmstadt.de state may suppress PI: In a collision of atoms in spinstretched states the total spin of the reactants is larger than the total spin of the products.…”

Section: Introductionmentioning

confidence: 99%

Heteronuclear collisions between laser-cooled metastable neon atoms

et al. 2012

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We investigate heteronuclear collisions in isotope mixtures of laser-cooled metastable ( 3 P2) neon. Experiments are performed with spin-polarized atoms in a magnetic trap for all two-isotope combinations of the stable neon isotopes 20 Ne, 21 Ne, and 22 Ne. We determine the rate coefficients for heteronuclear ionizing collisions to β21,20 = (3.9 ± 2.7) × 10 −11 cm 3 /s, β22,20 = (2.6 ± 0.7) × 10 −11 cm 3 /s, and β21,22 = (3.9 ± 1.9) × 10 −11 cm 3 /s. We also study heteronuclear elastic collision processes and give upper bounds for heteronuclear thermal relaxation cross sections. This work significantly extends the limited available experimental data on heteronuclear ionizing collisions for laser-cooled atoms involving one or more rare gas atoms in a metastable state. I. INTRODUCTIONDue to their high internal energy which surpasses the ionization energy of almost all neutral atomic and molecular collision partners, metastable rare-gas atoms (Rg*) prepared by laser cooling techniques [1] present a unique class of atoms for the investigation of cold and ultracold collisions [2]. With lifetimes ranging from 14.73 s (neon)[3] to 7870 s (helium) [4], the first excited metastable states present effective ground states for applying standard laser cooling techniques. The resulting extremely low kinetic energy of the laser-cooled atoms (≈ 10 −10 eV) stands in strong contrast to the high internal energy between 8 eV (xenon) and 20 eV (helium). This offers unique conditions not accessible with samples of lasercooled alkali-metal atoms. In particular, the high internal energy of the metastable state allows for Penning (PI) and associative (AI) ionizing collisions,to dominate losses in trapped Rg* samples at high densities. Since direct detection of the collision products (using electron multipliers) as well as of the remaining Rg* atoms is possible with high efficiency, detailed studies of homonuclear ionizing collisions have been carried out for all rare gas elements (see [1] for an overview). Additional motivation for these investigations arises from the fact, that favorable rate coefficients for inelastic but also for elastic collisions are essential for the achievement of quantum degeneracy which for Rg* atoms so far has only been demonstrated for 4 He [5-8] and 3 He [9]. For unpolarized Rg* samples, two-body loss rate coefficients for PI [10] between β = 6 × 10 −11 cm 3 /s for 132 Xe [11] and β = 1 × 10 −9 cm 3 /s for 22 Ne [12] have been measured. Spin polarizing the atoms to a spin-stretched * gerhard.birkl@physik.tu-darmstadt.de state may suppress PI: In a collision of atoms in spinstretched states the total spin of the reactants is larger than the total spin of the products. Thus, if spin is conserved, PI collisions should be significantly reduced. In the case of He* in the 3 S 1 state, a suppression of four orders of magnitude has been observed [7,13]. For the heavier rare gases, however, the metastable state 3 P 2 is formed by an exited s electron and a p 5 core with orbital momentum l = 1. This leads to an anisot...

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“…The atoms are then collected in a magneto-optical trap and further cooled with optical molasses to approximately 10 µK. We characterize the cold neutral atoms by optical absorption imaging [10]. This measurement provides the density and size of the atomic cloud and the number of atoms in the sample.…”

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confidence: 99%

Creation of an Ultracold Neutral Plasma

et al. 1999

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We report the creation of an ultracold neutral plasma by photoionization of laser-cooled xenon atoms. The charge carrier density is as high as 2 × 10 9 cm −3 , and the temperatures of electrons and ions are as low as 100 mK and 10 µK, respectively. Plasma behavior is evident in the trapping of electrons by the positive ion cloud when the Debye screening length becomes smaller than the size of the sample. We produce plasmas with parameters such that both electrons and ions are strongly coupled.The study of ionized gases in neutral plasma physics spans temperatures ranging from 10 16 K in the magnetosphere of a pulsar to 300 K in the earth's ionosphere [1]. At lower temperatures the properties of plasmas are expected to differ significantly. For instance, three-body recombination which is prevalent in high temperature plasmas, should be suppressed [2]. If the thermal energy of the particles is less than the Coulomb interaction energy, the plasma becomes strongly coupled, and the usual hydrodynamic equations of motion and collective mode dispersion relations are no longer valid [3]. Strongly coupled plasmas are difficult to produce in the laboratory and only a handful of examples exist [4], but such plasmas do occur naturally in astrophysical systems.In this work we create an ultracold neutral plasma with an electron temperature as low as T e = 100 mK, an ion temperature as low as T i = 10 µK, and densities as high as n = 2×10 9 cm −3 . We obtain this novel plasma by photoionization of laser-cooled xenon atoms. Within the experimentally accessible ranges of temperatures and densities both components can be simultaneously strongly coupled. A simple model describes the evolution of the plasma in terms of the competition between the kinetic energy of the electrons and the Coulomb attraction between electrons and ions. A numerical calculation accurately reproduces the data.Photoionization and laser-cooling have been used before in plasma experiments. Photoionization in a 600 K Cs vapor cell produced a plasma with T e ≥ 2000 K [5], and a strongly coupled non-neutral plasma was created by laser-cooling magnetically trapped Be + ions [6]. A plasma is often defined as an ionized gas in which the charged particles exhibit collective effects [7]. The length scale which divides individual particle behavior and collective behavior is the Debye screening length λ D . It is the distance over which an electric field is screened by redistribution of electrons in the plasma, and is given by λ D = ǫ 0 k B T e /e 2 n. Here, ǫ 0 is the electric permittivity of vacuum, k B is the Boltzmann constant, and e is the elementary charge. An ionized gas is not a plasma unless the Debye length is smaller than the size of the system [7]. In our experiment, the Debye length can be as low as 500 nm, while the size of the sample is σ ≈ 200 µm. The condition λ D < σ for creating a plasma is thus easily fulfilled.The atomic system we use is metastable xenon in the 6s [3/2] 2 state. This state has a lifetime of 43 s [8] and can be treated as the groun...

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Optical Control of Ultracold Collisions in Metastable Xenon

Cited by 86 publications

References 13 publications

Heteronuclear ionizing collisions between laser-cooled metastable helium atoms

Heteronuclear ionizing collisions between laser-cooled metastable helium atoms

Heteronuclear collisions between laser-cooled metastable neon atoms

Creation of an Ultracold Neutral Plasma

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