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

Optimisation d'ondes de matière cohérentes pour l'interférométrie atomique de précision

Depuis une dizaine d'années, le développement des techniques de refroidissement laser et de piégeage atomique a permis la réalisation d'une multitude de dispositifs et de capteurs basés sur les atomes froids. De la réalisation d'horloges atomiques très précises à la mesure des constantes fondamentales de la physique, ces dispositifs repoussent en permanence les limites des phénomènes quantiques explorés.Une technique très commune mise en pratique dans ces expériences implique l'interférométrie atomique, où la nature ondulatoire de la matière est prédominante proche de la température du zéro absolu. Les interféromètres atomiques atteignent un niveau de précision permettant de tester les principes et les prédictions fondamentales de la physique moderne, comme le principe d'équivalence faible de Einstein ou la détection des ondes gravitationnelles par exemple. Ces expériences nécessitent des durées longues pour les mesures interférométriques, de l'ordre de (ou supérieures à) quelques secondes, et des sources à ondes de matière optimisées, dont la dynamique est parfaitement contrôlée. Ces expériences nécessitent une préparation et une collimation contrôlée d'ensembles atomiques en expansion, avec des vitesses inférieures à 100 micromètres par seconde, ce qui correspond à des températures T < nK. Dans mon projet de nature théorique, nous nous attachons à développer l'ingénierie quantique des états de condensats de Bose-Einstein (BEC) d'atomes alcalins remplissant ces conditions inhabituelles de température.Pour réaliser ce type d'expériences, les expérimentateurs ont recours à l'utilisation des puces atomiques, qui sont des surfaces compactes micro-structurées. L'usage de ces dernières introduit des problèmes du type interaction atome-surface. Pour s'assurer du bon déroulement de l'expérience, on doit transporter le condensat loin de la puce sans l'exciter. On présente un ensemble d'outils théoriques pour manipuler ces BECs. La dynamique des condensats est traitée en calculant l'évolution temporelle d'un paquet d'ondes 3D avec un grand nombre d'atomes en interaction, en résolvant numériquement l'équation de Gross-Pitaevskii (GPE). Une technique dite de «scaling», qui consiste à réadapter les grilles est utilisée pour traiter la dynamique quantique 3D des condensats en phase d'expansion, qui ont rapidement de grandes tailles. Cette technique est purement numérique. Une application est prévue pour l'expérience «Quantus» qui se déroule en micro-gravité dans la tour de Brême. De plus, différentes procédures semi-classiques ont été détaillées pour traiter le transport macroscopique cohérent des condensats sur un dispositif à puce atomique. Des approches classiques basées sur le principe de la rétro-ingénierie et du raccourci vers l'adiabaticité (STA) ont ensuite été détaillées. Les premiers calculs basés sur l'ingénierie inverse et la GPE nous ont permis de prédire des conditions de transport réalistes pour préparer un nuage atomique optimisé pour l'interférométrie atomique, avec des vitesses d'expansion dans le domaine de sous-10pk. Cependant, cette approche souffre de certaines limites en termes de contrôle de l'état final du système. Afin d'aller plus loin, un nouveau modèle utilisant la théorie du contrôle optimal (OCT) est détaillé et développé. Ces approches permettent de prédire les variations des paramètres de contrôle (champ magnétique temporel par exemple) à réaliser pour transporter de manière parfaitement maîtrisée le condensat loin de la puce atomique. Le contrôle optimal du transport des BECs, une méthode qui nous a permis de montrer qu'il était possible de préparer l'état fondamental du piège final lors d'un transport rapide.Dans une dernière étape, nous utilisons cette technique optimale pour collimater de manière optimale le BEC en utilisant le delta kick-collimation (DKC) pour assurer une séquence temporelle plus courte et pour préparer l'entrée d'onde de matière la plus froide pour l'étape d'interférométrie.Since the development of laser cooling and trapping of atoms, a multitude of cold-atom-based devices and sensors were realized. From measurements of fundamental constants, these devices are pushing the boundaries of explored quantum phenomena. A very common technique put in practice in these experiments involves atom interferometry, where the wave nature of matter is predominant close to absolute zero temperatures.Atom interferometers reached a level of precision allowing to test of fundamental principles and predictions at the heart of modern physics controversies such as Einstein's weak equivalence principle, the detection of gravitational waves, or probing the quantum superposition principle at macroscopic scales. Going beyond state-of-the-art performance in these experiments requires long interferometer durations, of the order of several seconds, and optimized matter-wave sources whose dynamics are well controlled.The requirements imposed on atom sources for interferometry experiments of high precision are quite demanding. They require preparation and modeling of collimated atomic ensembles expanding with velocities not larger than 100 micrometers per second (i.e. sub-nK equivalent expansion temperatures).Quantum engineered states of Bose-Einstein condensates (BECs) of alkaline atoms fulfilling these unusual requirements in temperature, and therefore in observation times, will be studied theoretically. The matter-wave lensing to a few pK expansion temperatures of a single-component Rb-87 degenerate gas will be studied and directly compared to the outcome of novel experiments performed in the group of E. Rasel at the Institute of Quantum Optics in Hanover.Optimized models of the atomic dynamics should allow, at a later stage, to take the experiments to the unprecedented level of control necessary to challenge current tests of fundamental physics laws. The aim is to develop new theoretical toolboxes to tackle these specific needs in close exchange with experimentalists. A set of theoretical tools are presented to manipulate the BECs. The condensate dynamics is processed by calculating the time evolution of a 3D wave packet with a large number of interacting atoms, by solving numerically the time-dependent Gross-Pitaevskii (GPE) equation. A so-called "scaling" technique, which consists of re-adapting the grids is used to process the 3D quantum dynamics of condensates in the expansion phase, which rapidly have large sizes. This technique is purely numerical. An application is planned for the "Quantus" experiment that takes place in micro-gravity in the Bremen Tower. Moreover, different semi-classical procedures were detailed to treat the coherent macroscopic matter-wave transport on atom chip devices. Classical approaches based on the principle of reverse engineering and short-cut-to adiabaticity (STA) were then detailed. Early calculations based on reverse engineering and GPE allowed us to predict realistic transport conditions to prepare an atomic cloud optimized for atomic interferometry, with expansion velocities in the domain of sub-10pk. However, this approach suffers from certain limitations in terms of control of the final state of the system. To go further, a new model using optimal control theory (OCT) is detailed and developed. These approaches allow us to predict the variations of the control parameters (time-dependent magnetic field for example) that have to be realized to transport in a perfectly controlled way the condensate far from the atomic chip. Optimal control of condensate transport, a method that has allowed us to show that it was possible to prepare the ground state of the final trap during rapid transport.In a final step, we get use of this optimal technique to optimally collimate the BEC using the delta kick-collimation (DKC) to ensure a shorter temporal sequence and to prepare the coldest matter-wave input for the interferometry step

Optimisation d'ondes de matière cohérentes pour l'interférométrie atomique de précision

Since the development of laser cooling and trapping of atoms, a multitude of cold-atom-based devices and sensors were realized. From measurements of fundamental constants, these devices are pushing the boundaries of explored quantum phenomena. A very common technique put in practice in these experiments involves atom interferometry, where the wave nature of matter is predominant close to absolute zero temperatures.Atom interferometers reached a level of precision allowing to test of fundamental principles and predictions at the heart of modern physics controversies such as Einstein's weak equivalence principle, the detection of gravitational waves, or probing the quantum superposition principle at macroscopic scales. Going beyond state-of-the-art performance in these experiments requires long interferometer durations, of the order of several seconds, and optimized matter-wave sources whose dynamics are well controlled.The requirements imposed on atom sources for interferometry experiments of high precision are quite demanding. They require preparation and modeling of collimated atomic ensembles expanding with velocities not larger than 100 micrometers per second (i.e. sub-nK equivalent expansion temperatures).Quantum engineered states of Bose-Einstein condensates (BECs) of alkaline atoms fulfilling these unusual requirements in temperature, and therefore in observation times, will be studied theoretically. The matter-wave lensing to a few pK expansion temperatures of a single-component Rb-87 degenerate gas will be studied and directly compared to the outcome of novel experiments performed in the group of E. Rasel at the Institute of Quantum Optics in Hanover.Optimized models of the atomic dynamics should allow, at a later stage, to take the experiments to the unprecedented level of control necessary to challenge current tests of fundamental physics laws. The aim is to develop new theoretical toolboxes to tackle these specific needs in close exchange with experimentalists. A set of theoretical tools are presented to manipulate the BECs. The condensate dynamics is processed by calculating the time evolution of a 3D wave packet with a large number of interacting atoms, by solving numerically the time-dependent Gross-Pitaevskii (GPE) equation. A so-called "scaling" technique, which consists of re-adapting the grids is used to process the 3D quantum dynamics of condensates in the expansion phase, which rapidly have large sizes. This technique is purely numerical. An application is planned for the "Quantus" experiment that takes place in micro-gravity in the Bremen Tower. Moreover, different semi-classical procedures were detailed to treat the coherent macroscopic matter-wave transport on atom chip devices. Classical approaches based on the principle of reverse engineering and short-cut-to adiabaticity (STA) were then detailed. Early calculations based on reverse engineering and GPE allowed us to predict realistic transport conditions to prepare an atomic cloud optimized for atomic interferometry, with expansion velocities in the domain of sub-10pk. However, this approach suffers from certain limitations in terms of control of the final state of the system. To go further, a new model using optimal control theory (OCT) is detailed and developed. These approaches allow us to predict the variations of the control parameters (time-dependent magnetic field for example) that have to be realized to transport in a perfectly controlled way the condensate far from the atomic chip. Optimal control of condensate transport, a method that has allowed us to show that it was possible to prepare the ground state of the final trap during rapid transport.In a final step, we get use of this optimal technique to optimally collimate the BEC using the delta kick-collimation (DKC) to ensure a shorter temporal sequence and to prepare the coldest matter-wave input for the interferometry step.Depuis une dizaine d'années, le développement des techniques de refroidissement laser et de piégeage atomique a permis la réalisation d'une multitude de dispositifs et de capteurs basés sur les atomes froids. De la réalisation d'horloges atomiques très précises à la mesure des constantes fondamentales de la physique, ces dispositifs repoussent en permanence les limites des phénomènes quantiques explorés.Une technique très commune mise en pratique dans ces expériences implique l'interférométrie atomique, où la nature ondulatoire de la matière est prédominante proche de la température du zéro absolu. Les interféromètres atomiques atteignent un niveau de précision permettant de tester les principes et les prédictions fondamentales de la physique moderne, comme le principe d'équivalence faible de Einstein ou la détection des ondes gravitationnelles par exemple. Ces expériences nécessitent des durées longues pour les mesures interférométriques, de l'ordre de (ou supérieures à) quelques secondes, et des sources à ondes de matière optimisées, dont la dynamique est parfaitement contrôlée. Ces expériences nécessitent une préparation et une collimation contrôlée d'ensembles atomiques en expansion, avec des vitesses inférieures à 100 micromètres par seconde, ce qui correspond à des températures T < nK. Dans mon projet de nature théorique, nous nous attachons à développer l'ingénierie quantique des états de condensats de Bose-Einstein (BEC) d'atomes alcalins remplissant ces conditions inhabituelles de température.Pour réaliser ce type d'expériences, les expérimentateurs ont recours à l'utilisation des puces atomiques, qui sont des surfaces compactes micro-structurées. L'usage de ces dernières introduit des problèmes du type interaction atome-surface. Pour s'assurer du bon déroulement de l'expérience, on doit transporter le condensat loin de la puce sans l'exciter. On présente un ensemble d'outils théoriques pour manipuler ces BECs. La dynamique des condensats est traitée en calculant l'évolution temporelle d'un paquet d'ondes 3D avec un grand nombre d'atomes en interaction, en résolvant numériquement l'équation de Gross-Pitaevskii (GPE). Une technique dite de «scaling», qui consiste à réadapter les grilles est utilisée pour traiter la dynamique quantique 3D des condensats en phase d'expansion, qui ont rapidement de grandes tailles. Cette technique est purement numérique. Une application est prévue pour l'expérience «Quantus» qui se déroule en micro-gravité dans la tour de Brême. De plus, différentes procédures semi-classiques ont été détaillées pour traiter le transport macroscopique cohérent des condensats sur un dispositif à puce atomique. Des approches classiques basées sur le principe de la rétro-ingénierie et du raccourci vers l'adiabaticité (STA) ont ensuite été détaillées. Les premiers calculs basés sur l'ingénierie inverse et la GPE nous ont permis de prédire des conditions de transport réalistes pour préparer un nuage atomique optimisé pour l'interférométrie atomique, avec des vitesses d'expansion dans le domaine de sous-10pk. Cependant, cette approche souffre de certaines limites en termes de contrôle de l'état final du système. Afin d'aller plus loin, un nouveau modèle utilisant la théorie du contrôle optimal (OCT) est détaillé et développé. Ces approches permettent de prédire les variations des paramètres de contrôle (champ magnétique temporel par exemple) à réaliser pour transporter de manière parfaitement maîtrisée le condensat loin de la puce atomique. Le contrôle optimal du transport des BECs, une méthode qui nous a permis de montrer qu'il était possible de préparer l'état fondamental du piège final lors d'un transport rapide.Dans une dernière étape, nous utilisons cette technique optimale pour collimater de manière optimale le BEC en utilisant le delta kick-collimation (DKC) pour assurer une séquence temporelle plus courte et pour préparer l'entrée d'onde de matière la plus froide pour l'étape d'interférométrie

Distribution and accumulation of metals and metalloids in planktonic food webs of the Mediterranean Sea (MERITE-HIPPOCAMPE campaign)

International audienceParticle-size classes (7 fractions from 0.8 to 2000 µm) were collected in the deep chlorophyll maximum along a Mediterranean transect including the northern coastal zone (bays of Toulon and Marseilles, France), the offshore zone (near the North Balearic Thermal Front), and the southern coastal zone (Gulf of Gabès, Tunisia). Concentrations of biotic metals and metalloids (As, Cd, Cr, Cu, Fe, Mn, Ni, Sb, V, Zn) bound to living or dead organisms and faecal pellets were assessed by phosphorus normalisation. Biotic metals and metalloids concentrations (except Cr, Mn, and V) were higher in the offshore zone than in the coastal zones. In addition, biotic Sb and V concentrations appeared to be affected by atmospheric deposition, and biotic Cr concentrations appeared to be affected by local anthropogenic inputs. Essential elements (Cd, Cu, Fe, Mn, Ni, V, Zn) were very likely controlled both by the metabolic activity of certain organisms (nanoeukaryotes, copepods) and trophic structure. In the northern coastal zone, biomagnification of essential elements was controlled by copepods activities. In the offshore zone, metals and metalloids were not biomagnified probably due to homeostasis regulatory processes in organisms. In the southern coastal zone, biomagnification of As, Cu, Cr, Sb could probably induce specific effects within the planktonic network

Providencia entomophila sp. nov., a new bacterial species associated with major olive pests in Tunisia.

Bioprospection for potential microbial biocontrol agents associated with three major insect pests of economic relevance for olive cultivation in the Mediterranean area, namely the olive fly, Bactrocera oleae, the olive moth, Prays oleae, and the olive psyllid, Euphyllura olivina, led to the isolation of several strains of readily cultivable Gram-negative, rod-shaped bacteria from Tunisian olive orchards. Determination of 16S ribosomal RNA encoding sequences identified the bacteria as members of the taxonomic genus Providencia (Enterobacterales; Morganellaceae). A more detailed molecular taxonomic analysis based on a previously established set of protein-encoding marker genes together with DNA-DNA hybridization and metabolic profiling studies led to the conclusion that the new isolates should be organized in a new species within this genus. With reference to their original insect association, the designation "Providencia entomophila" is proposed here for this hypothetical new taxon

Space-borne Bose–Einstein condensation for precision interferometry

Owing to the low-gravity conditions in space, space-borne laboratories enable experiments with extended free-fall times. Because Bose–Einstein condensates have an extremely low expansion energy, space-borne atom interferometers based on Bose–Einstein condensation have the potential to have much greater sensitivity to inertial forces than do similar ground-based interferometers. On 23 January 2017, as part of the sounding-rocket mission MAIUS-1, we created Bose–Einstein condensates in space and conducted 110 experiments central to matter-wave interferometry, including laser cooling and trapping of atoms in the presence of the large accelerations experienced during launch. Here we report on experiments conducted during the six minutes of in-space flight in which we studied the phase transition from a thermal ensemble to a Bose–Einstein condensate and the collective dynamics of the resulting condensate. Our results provide insights into conducting cold-atom experiments in space, such as precision interferometry, and pave the way to miniaturizing cold-atom and photon-based quantum information concepts for satellite-based implementation. In addition, space-borne Bose–Einstein condensation opens up the possibility of quantum gas experiments in low-gravity conditions1,2

Space-borne Bose-Einstein condensation for precision interferometry

Owing to the low-gravity conditions in space, space-borne laboratories enable experiments with extended free-fall times. Because Bose–Einstein condensates have an extremely low expansion energy, space-borne atom interferometers based on Bose–Einstein condensation have the potential to have much greater sensitivity to inertial forces than do similar ground-based interferometers. On 23 January 2017, as part of the sounding-rocket mission MAIUS-1, we created Bose–Einstein condensates in space and conducted 110 experiments central to matter-wave interferometry, including laser cooling and trapping of atoms in the presence of the large accelerations experienced during launch. Here we report on experiments conducted during the six minutes of in-space flight in which we studied the phase transition from a thermal ensemble to a Bose–Einstein condensate and the collective dynamics of the resulting condensate. Our results provide insights into conducting cold-atom experiments in space, such as precision interferometry, and pave the way to miniaturizing cold-atom and photon-based quantum information concepts for satellite-based implementation. In addition, space-borne Bose–Einstein condensation opens up the possibility of quantum gas experiments in low-gravity conditions

Contamination of planktonic food webs in the Mediterranean Sea: Setting the frame for the MERITE-HIPPOCAMPE oceanographic cruise (spring 2019)

International audienceThis paper looks at experiential feedback and the technical and scientific challenges tied to the MERITE-HIPPOCAMPE cruise that took place in the Mediterranean Sea in spring 2019. This cruise proposes an innovative approach to investigate the accumulation and transfer of inorganic and organic contaminants within the planktonic food webs. We present detailed information on how the cruise worked, including 1) the cruise track and sampling stations, 2) the overall strategy, based mainly on the collection of plankton, suspended particles and water at the deep chlorophyll maximum, and the separation of these particles and planktonic organisms into various size fractions, as well as the collection of atmospheric deposition, 3) the operations performed and material used at each station, and 4) the sequence of operations and main parameters analysed. The paper also provides the main environmental conditions that were prevailing during the campaign. Lastly, we present the types of articles produced based on work completed by the cruise that are part of this special issue