We report on the creation of a degenerate Fermi gas consisting of a balanced mixture of atoms in three different hyperfine states of 6 Li. This new system consists of three distinguishable Fermions with different and tunable interparticle scattering lengths a12, a13 and a23. We are able to prepare samples containing 5 · 10 4 atoms in each state at a temperature of about 215 nK, which corresponds to T /TF ≈ 0.37. We investigated the collisional stability of the gas for magnetic fields between 0 and 600 G and found a prominent loss feature at 130 G. From lifetime measurements we determined three-body loss coefficients, which vary over nearly three orders of magnitude.
Control over the motional degrees of freedom of atoms, ions, and molecules in a field-free environment enables unrivalled measurement accuracies but has yet to be applied to highly charged ions (HCIs), which are of particular interest to future atomic clock designs and searches for physics beyond the Standard Model. Here, we report on the Coulomb crystallization of HCIs (specifically (40)Ar(13+)) produced in an electron beam ion trap and retrapped in a cryogenic linear radiofrequency trap by means of sympathetic motional cooling through Coulomb interaction with a directly laser-cooled ensemble of Be(+) ions. We also demonstrate cooling of a single Ar(13+) ion by a single Be(+) ion-the prerequisite for quantum logic spectroscopy with a potential 10(-19) accuracy level. Achieving a seven-orders-of-magnitude decrease in HCI temperature starting at megakelvin down to the millikelvin range removes the major obstacle for HCI investigation with high-precision laser spectroscopy.
[1,2] efficient. In this letter we present the first waveguide chip designed to address a BEC along a row of independent junctions, which are separated by only 10 µm and have large atom-photon coupling. We describe the fully integrated, scalable design and demonstrate 11 junctions working as intended, using a low density cold atom cloud with as little as one atom on average in any one junction. Our device opens new possibilities for engineering quantum states of matter and light on a microscopic scale.Micro-fabricated chips are widely used to control clouds of ultra-cold atoms and BoseEinstein condensates [3,4]. Recently, the idea has been extended to the control of ions [5] and similar possibilities exist for molecules [6]. This atom-chip technology provides a way to miniaturise existing atomic physics devices. In addition, it promises new devices that take advantage of the elementary quantum nature of atoms [7][8][9] [16][17][18] or otherwise attached [19] to a chip. A pair of these fibres looking into each other can be used to detect an atom cloud and can reach close to single atom sensitivity [17]. When reflective coatings are added, the gap between two fibres [1,20] or between one fibre and a micro-fabricated mirror [21] becomes a Fabry-Perot resonator. Similarly, a fibre can be coupled to a micro-disk resonator [22,23]. These devices can achieve strong atom-photon coupling for applications in quantum information processing.This letter reports a further order of magnitude scale reduction, in which the 125 µm-diameter optical fibre is replaced by an integrated waveguide only 10 µm across, with a 4 µm square core. Since a BEC is typically ∼ 100 µm long, this size reduction opens the new 3 possibility of intersecting a BEC with many closely spaced atom-photon junctions of high coupling strength. In our device, illustrated in Figure 1, a trench containing the cold atoms cuts through an array of 12 waveguides spaced by 10 µm. This design is a significant advance in the way that photons can be coupled to ultracold atoms.In order to characterise the chip, we have released cold atoms into a junction to measure its sensitivity and to demonstrate the basics of its operation. Every few seconds, 87 Rb atoms are cooled and collected from a room-temperature vapour by a Low-Velocity Intense Source (LVIS), then transferred to a magneto-optical trap (MOT) about 4 mm from the chip surface, where the atom density is up to 4 × 10 −2 atoms/µm 3 and the temperature is ∼ 100µK. We push this cloud towards the chip just before switching off the MOT light and magnetic field, thereby launching the atoms at 40 cm/s into the trench. The light beams from the waveguides diverge only slightly as they cross the trench, with w -the 1/e radius of the field -growing from 2.2 µm to 2.8 µm. Since the width of the trench is L = 16 µm, any given beam interacts with roughly one to four atoms of the cloud as they pass through.Each atom crosses the light in ∼ 7 µs, scattering up to 130 photons (the fully saturated rate is Γ/2 = 1.9 × 10 7 s −1 ).Wi...
We develop an intuitive model of 2D microwave near-fields in the unusual regime of centimeter waves localized to tens of microns. Close to an intensity minimum, a simple effective description emerges with five parameters which characterize the strength and spatial orientation of the zero and first order terms of the near-field, as well as the field polarization. Such a field configuration is realized in a microfabricated planar structure with an integrated microwave conductor operating near 1 GHz. We use a single 9 Be + ion as a high-resolution quantum sensor to measure the field distribution through energy shifts in its hyperfine structure. We find agreement with simulations at the sub-micron and few-degree level. Our findings give a clear and general picture of the basic properties of oscillatory 2D near-fields with applications in quantum information processing, neutral atom trapping and manipulation, chip-scale atomic clocks, and integrated microwave circuits.PACS numbers: 03.67. Bg, 03.67.Lx, 37.10.Rs, 37.10.Ty, 37.90.+j Static or oscillatory electromagnetic fields have important applications in atomic and molecular physics for atom trapping and manipulation. Neutral atoms can be trapped in static magnetic fields in different types of magnetic traps [1]. Atomic ions can be trapped either in superpositions of static and oscillatory electric fields (Paul trap) or in superimposed static electromagnetic fields (Penning trap) [2]. Atom and molecule decelerators rely on the distortion of atomic energy levels by spatially inhomogeneous fields [3]. Common to all of these field configurations is that their basic properties can be well described in terms of static solutions to the field equations and that the behavior of the field near its intensity minimum is often critical to the application. Prominent examples include Majorana losses in neutral atom magnetic traps [1] and micromotion in Paul traps [4].Recently, motivated by advances in microfabricated atom traps, interest has grown in microwave near-fields which originate from microfabricated structures. Dimensions are typically small compared to the wavelength, but for the relatively high frequencies involved, eddy currents and phase effects become important, and the resulting field patterns are much richer than in the quasistatic case. Examples include rf potentials for neutral atoms [5] with applications in atom interferometry, quantum gates [6,7] and chip-scale atomic clocks [8] as well as microwave near-fields for trapped-ion quantum logic [9][10][11]. Also, neutral atomic clouds [12] and single ions [13] have been used to characterise near-fields at sub-mm length scales or measure magnetic field gradients [14]. The behavior of these high-frequency oscillatory fields may also become relevant for coupling atomic and molecular quantum systems to microwave circuits in the quantum regime [15,16]. Of particular importance in this context are 2D field configurations which can be realized e. g. in integrated waveguides. Notwithstanding the strong experimental int...
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