| 1. |
- Krueger, P., et al.
(författare)
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Potential roughness near lithographically fabricated atom chips
- 2007
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 76:6
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Tidskriftsartikel (refereegranskat)abstract
- Potential roughness has been reported to severely impair experiments in magnetic microtraps. We show that these obstacles can be overcome as we measure disorder potentials that are reduced by two orders of magnitude near lithographically patterned high-quality gold layers on semiconductor atom chip substrates. The spectrum of the remaining field variations exhibits a favorable scaling. A detailed analysis of the magnetic field roughness of a 100-mu m-wide wire shows that these potentials stem from minute variations of the current flow caused by local properties of the wire rather than merely from rough edges. A technique for further reduction of potential roughness by several orders of magnitude based on time-orbiting magnetic fields is outlined.
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| 2. |
- Kruger, P., et al.
(författare)
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Ultracold atoms on atom chips : Manipulation at the mu m distance scale
- 2005
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Ingår i: ATOMIC PHYSICS 19. - : AIP. ; , s. 144-153
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Konferensbidrag (refereegranskat)abstract
- Miniaturized potentials near the surface of atom chips can be used as flexible and versatile tools for the manipulation of ultracold atoms on a microscale. The full scope of possibilities is only accessible if atom‐surface distances can be reduced to microns. We discuss experiments in this regime and potential obstacles and solutions. We show that appropriate fabrication techniques lead to a reduction of disorder potentials so that one‐dimensional condensates can be prepared. We demonstrate how electrostatic potentials can be used to modify magnetic trapping potentials and how they can be used to study condensate formation in situations of different dimensionality. © 2005 American Institute of Physics
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| 3. |
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| 4. |
- Schumm, T., et al.
(författare)
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A double well interferometer on an atom chip
- 2006
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Ingår i: Quantum Information Processing. - : Springer Science and Business Media LLC. - 1570-0755 .- 1573-1332. ; 5:6, s. 537-558
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Tidskriftsartikel (refereegranskat)abstract
- Radio-Frequency coupling between magnetically trapped atomic states allows to create versatile adiabatic dressed state potentials for neutral atom manipulation. Most notably, a single magnetic trap can be split into a double well by controlling amplitude and frequency of an oscillating magnetic field. We use this to build an integrated matter wave interferometer on an atom chip. Transverse splitting of quasi one-dimensional Bose-Einstein condensates over a wide range from 3 to 80 mu m is demonstrated, accessing the tunnelling regime as well as completely isolated sites. By recombining the two split BECs in time of flight expansion, we realize a matter wave interferometer. The observed interference pattern exhibits a stable relative phase of the two condensates, clearly indicating a coherent splitting process. Furthermore, we measure and control the deterministic phase evolution throughout the splitting process. RF induced potentials are especially suited for integrated micro manipulation of neutral atoms on atom chips: designing appropriate wire patterns enables control over the created potentials to the (nanometer) precision of the fabrication process. Additionally, hight local RF amplitudes can be obtained with only moderate currents. This new technique can be directly implemented in many existing atom chip experiments.
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| 5. |
- Schumm, T., et al.
(författare)
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Matter-wave interferometry in a double well on an atom chip
- 2005
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Ingår i: Nature Physics. - : Springer Science and Business Media LLC. - 1745-2473 .- 1745-2481. ; 1:1, s. 57-62
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Tidskriftsartikel (refereegranskat)abstract
- Matter-wave interference experiments enable us to study matter at its most basic, quantum level and form the basis of high-precision sensors for applications such as inertial and gravitational field sensing. Success in both of these pursuits requires the development of atom-optical elements that can manipulate matter waves at the same time as preserving their coherence and phase. Here, we present an integrated interferometer based on a simple, coherent matter-wave beam splitter constructed on an atom chip. Through the use of radio-frequency-induced adiabatic double-well potentials, we demonstrate the splitting of Bose-Einstein condensates into two clouds separated by distances ranging from 3 to 80 mu m, enabling access to both tunnelling and isolated regimes. Moreover, by analysing the interference patterns formed by combining two clouds of ultracold atoms originating from a single condensate, we measure the deterministic phase evolution throughout the splitting process. We show that we can control the relative phase between the two fully separated samples and that our beam splitter is phase-preserving.
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| 6. |
- Ebrahim, Shimaa A M, et al.
(författare)
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Drosophila Avoids Parasitoids by Sensing Their Semiochemicals via a Dedicated Olfactory Circuit.
- 2015
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Ingår i: PLoS Biology. - : Public Library of Science (PLoS). - 1545-7885. ; 13:12
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Tidskriftsartikel (refereegranskat)abstract
- Detecting danger is one of the foremost tasks for a neural system. Larval parasitoids constitute clear danger to Drosophila, as up to 80% of fly larvae become parasitized in nature. We show that Drosophila melanogaster larvae and adults avoid sites smelling of the main parasitoid enemies, Leptopilina wasps. This avoidance is mediated via a highly specific olfactory sensory neuron (OSN) type. While the larval OSN expresses the olfactory receptor Or49a and is tuned to the Leptopilina odor iridomyrmecin, the adult expresses both Or49a and Or85f and in addition detects the wasp odors actinidine and nepetalactol. The information is transferred via projection neurons to a specific part of the lateral horn known to be involved in mediating avoidance. Drosophila has thus developed a dedicated circuit to detect a life-threatening enemy based on the smell of its semiochemicals. Such an enemy-detecting olfactory circuit has earlier only been characterized in mice and nematodes.
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| 7. |
- Lesanovsky, I., et al.
(författare)
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Adiabatic radio-frequency potentials for the coherent manipulation of matter waves
- 2006
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622. ; 73:3
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Tidskriftsartikel (refereegranskat)abstract
- Adiabatic dressed state potentials are created when magnetic substates of trapped atoms are coupled by a radio-frequency field. We discuss their theoretical foundations and point out fundamental advantages over potentials purely based on static fields. The enhanced flexibility enables one to implement numerous configurations, including double wells, Mach-Zehnder, and Sagnac interferometers which even allows for internal state-dependent atom manipulation. These can be realized using simple and highly integrated wire geometries on atom chips.
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