Ein Materiewellenlinsensystem zur Kollimierung der Expansion eines Bose-Einstein Kondensates unter Schwerelosigkeit

Quantensensoren basierend auf Materiewelleninterferometrie können zur Vermessung einer Vielzahl verschiedenster physikalischer Größen verwendet werden. Die Anwendung reicht von der präzisen Bestimmung fundamentaler Naturkonstanten bis zur Vermessung inertialer Kräfte wie Beschleunigungen und Rotationen. Hiermit lassen sich bspw. quantenbasierte Inertialsensoren für Navigationsaufgaben, Gravimeter oder auch Gradiometer realisieren. Hierzu sind ultrakalte oder kondensierte atomare Ensembles notwendig, da die Sensitivität des Materiewelleninterferometers mit der Dauer des Interferometers skaliert. Im Rahmen dieser Arbeit wurde untersucht, inwiefern sich die Expansionseigenschaften eines Quantengases manipulieren lassen um die Detektierbarkeit auch nach Freifallzeiten von mehreren Sekunden zu gewahrleisten. Hierzu wurde eine kompakte und robuste Quelle quantenentarteter Gase in der Mikrogravitationsumgebung des Fallturm Bremen genutzt. Mit ihr lassen sich Bose-Einstein Kondensate aus 100.000 Rb-87 Atomen mit einer Repetitionsrate von 1 Hz und einer internen kinetischen Energie von 2 nK erzeugen. Eine kollektive Größenoszillation wird mit einer magnetischen Linse kombiniert um ein Materiewellenlinsensystem zu formen. Die Messkampagnen im Fallturm wurden von Simulationen begleitet, um quantitative Aussagen zu den Expansionseigenschaften und der Detektierbarkeit des Ensembles zu treffen. Es konnte gezeigt werden, dass sich die interne kinetische Energie eines Bose-Einstein Kondensates mithilfe des Materiewellenlinsensystems auf 38 pK reduzieren lässt. Ein derart manipuliertes atomares Ensemble konnte noch nach einer Freifallzeit von 2 s detektiert werden. Durch Extrapolation der Simulationsergebnisse konnte abgeschätzt werden, dass die Detektierbarkeit für bis zu 17 s gegeben wäre. Dies stellt einen herausragenden Eingangszustand fur künftige, vor allem weltraumgestützte Quantensensoren dar.Quantum-sensors based on matter-wave interferometrie can be used for measuring a multitude of different physical properties. The application ranges from the precise determination of fundamental natural constants to the measurement of inertial forces such as acceleration and rotation. This can be used to implement e. g. quantum-based inertial sensors for navigation tasks, gravimeters or gradiometers. For this, ultracold or condensed atomic ensembles are necessary, since the sensitivity of the matter-wave interferometer scales with the duration of the interferometer. In the context of this work, it was investigated to what extent the expansion properties of a quantum gas can be manipulated in order to ensure detectability even after free-fall times of several seconds. For this purpose, a compact and robust source of quantum degenerate gases in the microgravity environment of the Bremen drop tower was used [1–4]. It can be used to generate Bose-Einstein condensates of 100 000 87Rb atoms with a repetition rate of 1 Hz and an internal kinetic energy of 2 nK [4, 5]. A collective-mode excitation is combined with a magnetic lens to form a time-domain matter-wave lens system. The measurements in the drop tower were accompanied by simulations in order to make quantitative statements about the expansion properties and the ensembles detectability. It was shown that the internal kinetic energy of a Bose- Einstein condensate could be reduced to 38 pK using the matter-wave lens-system. An atomic ensemble manipulated in this way could still be detected after a free fall time of 2 s. By extrapolating the results of the simulations, it could be estimated that the detectability would be given for up to 17 s. This represents an outstanding initial state for future, especially space-based quantum sensors as proposed in STE-QUEST [6] or currently realized in BECCALDLR, BMWK/QUANTUS-V Fallturm/DLR 50WM1552-1557/E

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

Terrestrial Very-Long-Baseline Atom Interferometry:Workshop Summary

This document presents a summary of the 2023 Terrestrial Very-Long-Baseline Atom Interferometry Workshop hosted by CERN. The workshop brought together experts from around the world to discuss the exciting developments in large-scale atom interferometer (AI) prototypes and their potential for detecting ultralight dark matter and gravitational waves. The primary objective of the workshop was to lay the groundwork for an international TVLBAI proto-collaboration. This collaboration aims to unite researchers from different institutions to strategize and secure funding for terrestrial large-scale AI projects. The ultimate goal is to create a roadmap detailing the design and technology choices for one or more km-scale detectors, which will be operational in the mid-2030s. The key sections of this report present the physics case and technical challenges, together with a comprehensive overview of the discussions at the workshop together with the main conclusions

Quantum sensors for future gravity missions

Quantum sensors utilising atom interferometry offer new perspectives for future gravity missions. The atom interferometer therein promises long-term stable measurements, complementing or possibly replacing established sensor concepts. Several different experiments based on this principle demonstrated measurements of accelerations and gravity gradients. Additionally, dedicated setups showed operation in microgravity environments and tested concepts for space missions. A core feature is the robust generation of Bose-Einstein condensates with subsequent matter-wave collimation as a well-defined input state to enable extended times of free fall and suppress error terms. We will introduce the principle of atom interferometry, present the state of the art in interferometers with Bose-Einstein condensates, especially microgravity activities, and discuss concepts for the implementation in future space missions

Development and test of a real-size MRPC for CBM-TOF

In the CBM (Compressed Baryonic Matter) experiment constructed at the Facility for Anti-proton and Ion Research (Fair) at GSI, Darmstadt, Germany, MRPC(Multi-gap Resistive Plate Chamber) is adopted to construct the large TOF (Time-of-Flight) system to achieve an unprecedented precision of hadron identification, benefiting from its good time resolution, relatively high efficiency and low building price. We have developed a kind of double-ended readout strip MRPC. It uses low resistive glass to keep good performance of time resolution under high-rate condition. The differential double stack structure of 2x4 gas gaps help to reduce the required high voltage to half. There are 24 strips on one counter, and each is 270mm long, 7mm wide and the interval is 3mm. Ground is placed onto the MRPC electrode and feed through is carefully designed to match the 100 Ohm impedance of PADI electronics. The prototype of this strip MRPC has been tested with cosmic ray, a 98% efficiency and 60ps time resolution is gotten. In order to further examine the performance of the detector working under higher particle flux rate, the prototype has been tested in the 2014 October GSI beam time and 2015 February CERN beam time. In both beam times a relatively high rate of 1 kHz/cm2 was obtained. The calibration is done with CBM ROOT. A couple of corrections has been considered in the calibration and analysis process (including time-walk correction, gain correction, strip alignment correction and velocity correction) to access actual counter performances such as efficiency and time resolution. An efficiency of 97% and time resolution of 48ps are obtained. All these results show that the real-size prototype is fully capable of the requirement of the CBM-TOF, and new designs such as self-sealing are modified into the strip counter prototype to obtain even better performance.In the CBM (Compressed Baryonic Matter) experiment constructed at the Facility for Anti-proton and Ion Research (Fair) at GSI, Darmstadt, Germany, MRPC(Multi-gap Resistive Plate Chamber) is adopted to construct the large TOF (Time-of-Flight) system to achieve an unprecedented precision of hadron identification, benefiting from its good time resolution, relatively high efficiency and low construction price. Aiming at CBM TOF, we've developed a kind of double-ended readout strip MRPC which applies low resistive glass to keep good performance of time resolution under high-rate condition. There are 24 strips on one counter, and each is carefully designed to match the 100 Ω impedance of PADI electronics. The prototype of this strip MRPC has been tested with cosmic ray, a 98% efficiency and 60ps time resolution is gotten. In order to further examine the performance of the detector working under higher particle flux rate, the prototype has been tested in the 2014 October GSI beam time and 2015 February CERN beam time. In both beam times a relatively high rate of 1 kHz/cm(2) was obtained. The calibration is done with CBM ROOT, and an efficiency of 97% and time resolution of 48ps are obtained. All these results show that the real-size prototype is fully capable of the requirement of the CBM-TOF, and new designs such as self-sealed are modified into the strip counter prototype to obtain even better performance

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

Collective-Mode Enhanced Matter-Wave Optics

International audienceIn contrast to light, matter-wave optics of quantum gases deals with interactions even in free space and for ensembles comprising millions of atoms. We exploit these interactions in a quantum degenerate gas as an adjustable lens for coherent atom optics. By combining an interaction-driven quadrupole-mode excitation of a Bose-Einstein condensate (BEC) with a magnetic lens, we form a time-domain matter-wave lens system. The focus is tuned by the strength of the lensing potential and the oscillatory phase of the quadrupole mode. By placing the focus at infinity, we lower the total internal kinetic energy of a BEC comprising 101(37) thousand atoms in three dimensions to 3/2 kB⋅38+6−7 pK. Our method paves the way for free-fall experiments lasting ten or more seconds as envisioned for tests of fundamental physics and high-precision BEC interferometry, as well as opens up a new kinetic energy regime

Terrestrial Very-Long-Baseline Atom Interferometry: Workshop Summary

Summary of the Terrestrial Very-Long-Baseline Atom Interferometry Workshop held at CERN: https://indico.cern.ch/event/1208783/This document presents a summary of the 2023 Terrestrial Very-Long-Baseline Atom Interferometry Workshop hosted by CERN. The workshop brought together experts from around the world to discuss the exciting developments in large-scale atom interferometer (AI) prototypes and their potential for detecting ultralight dark matter and gravitational waves. The primary objective of the workshop was to lay the groundwork for an international TVLBAI proto-collaboration. This collaboration aims to unite researchers from different institutions to strategize and secure funding for terrestrial large-scale AI projects. The ultimate goal is to create a roadmap detailing the design and technology choices for one or more km-scale detectors, which will be operational in the mid-2030s. The key sections of this report present the physics case and technical challenges, together with a comprehensive overview of the discussions at the workshop together with the main conclusions

Terrestrial Very-Long-Baseline Atom Interferometry Workshop (TVLBAI 2023)

This document presents a summary of the 2023 Terrestrial Very-Long-Baseline Atom Interferometry Workshop hosted by CERN. The workshop brought together experts from around the world to discuss the exciting developments in large-scale atom interferometer (AI) prototypes and their potential for detecting ultralight dark matter and gravitational waves. The primary objective of the workshop was to lay the groundwork for an international TVLBAI proto-collaboration. This collaboration aims to unite researchers from different institutions to strategize and secure funding for terrestrial large-scale AI projects. The ultimate goal is to create a roadmap detailing the design and technology choices for one or more km-scale detectors, which will be operational in the mid-2030s. The key sections of this report present the physics case and technical challenges, together with a comprehensive overview of the discussions at the workshop together with the main conclusions

Terrestrial Very-Long-Baseline Atom Interferometry: Workshop Summary

Summary of the Terrestrial Very-Long-Baseline Atom Interferometry Workshop held at CERN: https://indico.cern.ch/event/1208783/This document presents a summary of the 2023 Terrestrial Very-Long-Baseline Atom Interferometry Workshop hosted by CERN. The workshop brought together experts from around the world to discuss the exciting developments in large-scale atom interferometer (AI) prototypes and their potential for detecting ultralight dark matter and gravitational waves. The primary objective of the workshop was to lay the groundwork for an international TVLBAI proto-collaboration. This collaboration aims to unite researchers from different institutions to strategize and secure funding for terrestrial large-scale AI projects. The ultimate goal is to create a roadmap detailing the design and technology choices for one or more km-scale detectors, which will be operational in the mid-2030s. The key sections of this report present the physics case and technical challenges, together with a comprehensive overview of the discussions at the workshop together with the main conclusions