49 research outputs found
Eine kompakte Quelle quantenentarteter Gase hohen Flusses für die Atominterferometrie unter Schwerelosigkeit
[no abstract
A high-flux BEC source for mobile atom interferometers
Quantum sensors based on coherent matter-waves are precise measurement
devices whose ultimate accuracy is achieved with Bose-Einstein condensates
(BEC) in extended free fall. This is ideally realized in microgravity
environments such as drop towers, ballistic rockets and space platforms.
However, the transition from lab-based BEC machines to robust and mobile
sources with comparable performance is a challenging endeavor. Here we report
on the realization of a miniaturized setup, generating a flux of quantum degenerate Rb atoms every 1.6s. Ensembles of atoms can be produced at a 1Hz rate. This is achieved by loading a
cold atomic beam directly into a multi-layer atom chip that is designed for
efficient transfer from laser-cooled to magnetically trapped clouds. The
attained flux of degenerate atoms is on par with current lab-based BEC
experiments while offering significantly higher repetition rates. Additionally,
the flux is approaching those of current interferometers employing Raman-type
velocity selection of laser-cooled atoms. The compact and robust design allows
for mobile operation in a variety of demanding environments and paves the way
for transportable high-precision quantum sensors.Comment: 22 pages, 6 figure
The cytohesin paralog Sec7 of Dictyostelium discoideum is required for phagocytosis and cell motility
Background: Dictyostelium harbors several paralogous Sec7 genes that encode members of three subfamilies of the Sec7 superfamily of guanine nucleotide exchange factors. One of them is the cytohesin family represented by three members in D. discoideum, SecG, Sec7 and a further protein distinguished by several transmembrane domains. Cytohesins are characterized by a Sec7-PH tandem domain and have roles in cell adhesion and migration. Results: We study here Sec7. In vitro its PH domain bound preferentially to phosphatidylinositol 3,4-bisphosphate (PI(3,4) P-2), phosphatidylinositol 4,5-bisphosphate (PI(4,5)P-2) and phosphatidylinositol 3,4,5-trisphosphate (PI(3,4,5)P-3). When following the distribution of GFP-Sec7 in vivo we observed the protein in the cytosol and at the plasma membrane. Strikingly, when cells formed pseudopods, macropinosomes or phagosomes, GFP-Sec7 was conspicuously absent from areas of the plasma membrane which were involved in these processes. Mutant cells lacking Sec7 exhibited an impaired phagocytosis and showed significantly reduced speed and less persistence during migration. Cellular properties associated with mammalian cytohesins like cell-cell and cell-substratum adhesion were not altered. Proteins with roles in membrane trafficking and signal transduction have been identified as putative interaction partners consistent with the data obtained from mutant analysis. Conclusions: Sec7 is a cytosolic component and is associated with the plasma membrane in a pattern distinctly different from the accumulation of PI(3,4,5)P-3. Mutant analysis reveals that loss of the protein affects cellular processes that involve membrane flow and the actin cytoskeleton
Microgravity facilities for cold atom experiments
Microgravity platforms enable cold atom research beyond experiments in typical laboratories by removing restrictions due to the gravitational acceleration or compensation techniques. While research in space allows for undisturbed experimentation, technological readiness, availability and accessibility present challenges for experimental operation. In this work we focus on the main capabilities and unique features of ground-based microgravity facilities for cold atom research. A selection of current and future scientific opportunities and their high demands on the microgravity environment are presented, and some relevant ground-based facilities are discussed and compared. Specifically, we point out the applicable free fall times, repetition rates, stability and payload capabilities, as well as programmatic and operational aspects of these facilities. These are contrasted with the requirements of various cold atom experiments. Besides being an accelerator for technology development, ground-based microgravity facilities allow fundamental and applied research with the additional benefit of enabling hands-on access to the experiment for modifications and adjustments
The Bose-Einstein Condensate and Cold Atom Laboratory
© 2020, The Author(s). Microgravity eases several constraints limiting experiments with ultracold and condensed atoms on ground. It enables extended times of flight without suspension and eliminates the gravitational sag for trapped atoms. These advantages motivated numerous initiatives to adapt and operate experimental setups on microgravity platforms. We describe the design of the payload, motivations for design choices, and capabilities of the Bose-Einstein Condensate and Cold Atom Laboratory (BECCAL), a NASA-DLR collaboration. BECCAL builds on the heritage of previous devices operated in microgravity, features rubidium and potassium, multiple options for magnetic and optical trapping, different methods for coherent manipulation, and will offer new perspectives for experiments on quantum optics, atom optics, and atom interferometry in the unique microgravity environment on board the International Space Station
iSense: a technology platform for cold atom based quantum technologies
A breakthrough in cold atom quantum technology is hindered by a bottleneck in the supporting technologies. We discuss a cold atom technology platform developed within the European iSense project, aiming at a gravimeter as demonstrator
Technology roadmap for cold-atoms based quantum inertial sensor in space
Recent developments in quantum technology have resulted in a new generation of sensors for measuring inertial quantities, such as acceleration and rotation. These sensors can exhibit unprecedented sensitivity and accuracy when operated in space, where the free-fall interrogation time can be extended at will and where the environment noise is minimal. European laboratories have played a leading role in this field by developing concepts and tools to operate these quantum sensors in relevant environment, such as parabolic flights, free-fall towers, or sounding rockets. With the recent achievement of Bose-Einstein condensation on the International Space Station, the challenge is now to reach a technology readiness level sufficiently high at both component and system levels to provide "off the shelf"payload for future generations of space missions in geodesy or fundamental physics. In this roadmap, we provide an extensive review on the status of all common parts, needs, and subsystems for the application of atom-based interferometers in space, in order to push for the development of generic technology components
Design of a dual species atom interferometer for space
Atom interferometers have a multitude of proposed applications in space
including precise measurements of the Earth's gravitational field, in
navigation & ranging, and in fundamental physics such as tests of the weak
equivalence principle (WEP) and gravitational wave detection. While atom
interferometers are realized routinely in ground-based laboratories, current
efforts aim at the development of a space compatible design optimized with
respect to dimensions, weight, power consumption, mechanical robustness and
radiation hardness. In this paper, we present a design of a high-sensitivity
differential dual species Rb/Rb atom interferometer for space,
including physics package, laser system, electronics and software. The physics
package comprises the atom source consisting of dispensers and a 2D
magneto-optical trap (MOT), the science chamber with a 3D-MOT, a magnetic trap
based on an atom chip and an optical dipole trap (ODT) used for Bose-Einstein
condensate (BEC) creation and interferometry, the detection unit, the vacuum
system for mbar ultra-high vacuum generation, and the
high-suppression factor magnetic shielding as well as the thermal control
system. The laser system is based on a hybrid approach using fiber-based
telecom components and high-power laser diode technology and includes all laser
sources for 2D-MOT, 3D-MOT, ODT, interferometry and detection. Manipulation and
switching of the laser beams is carried out on an optical bench using Zerodur
bonding technology. The instrument consists of 9 units with an overall mass of
221 kg, an average power consumption of 608 W (819 W peak), and a volume of 470
liters which would well fit on a satellite to be launched with a Soyuz rocket,
as system studies have shown.Comment: 30 pages, 23 figures, accepted for publication in Experimental
Astronom
STE-QUEST - Test of the Universality of Free Fall Using Cold Atom Interferometry
In this paper, we report about the results of the phase A mission study of the atom
interferometer instrument covering the description of the main payload elements, the
atomic source concept, and the systematic error sources
Space-borne Bose-Einstein condensation for precision interferometry
Space offers virtually unlimited free-fall in gravity. Bose-Einstein
condensation (BEC) enables ineffable low kinetic energies corresponding to
pico- or even femtokelvins. The combination of both features makes atom
interferometers with unprecedented sensitivity for inertial forces possible and
opens a new era for quantum gas experiments. On January 23, 2017, we created
Bose-Einstein condensates in space on the sounding rocket mission MAIUS-1 and
conducted 110 experiments central to matter-wave interferometry. In particular,
we have explored laser cooling and trapping in the presence of large
accelerations as experienced during launch, and have studied the evolution,
manipulation and interferometry employing Bragg scattering of BECs during the
six-minute space flight. In this letter, we focus on the phase transition and
the collective dynamics of BECs, whose impact is magnified by the extended
free-fall time. Our experiments demonstrate a high reproducibility of the
manipulation of BECs on the atom chip reflecting the exquisite control features
and the robustness of our experiment. These properties are crucial to novel
protocols for creating quantum matter with designed collective excitations at
the lowest kinetic energy scales close to femtokelvins.Comment: 6 pages, 4 figure