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The stability of matter-wave sensors benefits from interrogating large-particle-number atomic ensembles at high cycle rates. The use of quantum-degenerate gases with their low effective temperatures allows constraining systematic errors towards highest accuracy, but their production by evaporative cooling is costly with regard to both atom number and cycle rate. In this work, we report on the creation of cold matter-waves using a crossed optical dipole trap and shaping it by means of an all-optical matter-wave lens. We demonstrate the trade off between residual kinetic energy and atom number by short-cutting evaporative cooling and estimate the corresponding performance gain in matter-wave sensors. Our method is implemented using time-averaged optical potentials and hence easily applicable in optical dipole trapping setups., Comment: 10 pages, 5 figures

A major challenge common to all Galilean drop tests of the Universality of Free Fall (UFF) is the required control over the initial kinematics of the two test masses upon release due to coupling to gravity gradients and rotations. In this work, we present a two-fold mitigation strategy to significantly alleviate the source preparation requirements in space-borne quantum tests of the UFF, using a compensation mechanism together with signal demodulation. To this end, we propose a scheme to reduce the gravity-gradient-induced uncertainties in an atom-interferometric experiment in a dedicated satellite mission and assess the experimental feasibility. We find that with moderate parameters, the requirements on the initial kinematics of the two masses can be relaxed by five orders of magnitude. This does not only imply a significantly reduced mission time but also allows to reduce the differential acceleration uncertainty caused by co-location imperfections below the $10^{-18}$ level., Comment: 12 pages, 3 figures

We present a source engineering concept for a binary quantum mixture suitable as input for differential, precision atom interferometry with drift times of several seconds. To solve the non-linear dynamics of the mixture, we develop a set of scaling approach equations and verify their validity contrasting it to the one of a system of coupled Gross-Pitaevskii equations. This scaling approach is a generalization of the standard approach commonly used for single species. Its validity range is discussed with respect to intra- and inter-species interaction regimes. We propose a multi-stage, non-linear atomic lens sequence to simultaneously create dual ensembles with ultra-slow kinetic expansion energies, below 15 pK. Our scheme has the advantage of mitigating wave front aberrations, a leading systematic effect in precision atom interferometry., Comment: 38 pages, 7 figures

Matter-wave interferometry is a direct test of the quantum superposition principle for massive systems, and of collapse models. Here we show that the bounds placed by matter-wave interferometry depend weakly on the details of the collapse mechanism. Specifically, we compute the bounds on the CSL model and its variants, provided by the the KDTL interferometry experiment of Arndt's group [Phys. Chem. Chem. Phys., 2013, 15, 14696-14700], which currently holds the record of largest mass in interferometry. We also show that the CSL family of models emerges naturally by considering a minimal set of assumptions. In particular, we construct the dynamical map for the colored and dissipative Continuous Spontaneous Localization (cdCSL) model, which reduces to the CSL model and variants in the appropriate limits. In addition, we discuss the measure of macroscopicity based on the cdCSL model., 9 pages, 5 figures; accepted for publication in Physics Letters A (2017)

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 $4 \times 10^5$ quantum degenerate $^{87}$Rb atoms every 1.6$\,$s. Ensembles of $1 \times 10^5$ atoms can be produced at a 1$\,$Hz 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., 22 pages, 6 figures

We present a simple derivation of the interference pattern in matter-wave interferometry as predicted by a class of master equations, by using the density matrix formalism. We apply the obtained formulae to the most relevant collapse models, namely the Ghirardi-Rimini-Weber (GRW) model, the continuous spontaneous localization (CSL) model together with its dissipative (dCSL) and non-markovian generalizations (cCSL), the quantum mechanics with universal position localization (QMUPL) and the Di\'{o}si-Penrose (DP) model. We discuss the separability of the collapse models dynamics along the 3 spatial directions, the validity of the paraxial approximation and the amplification mechanism. We obtain analytical expressions both in the far field and near field limits. These results agree with those already derived in the Wigner function formalism. We compare the theoretical predictions with the experimental data from two relevant matter-wave experiments: the 2012 far-field experiment and the 2013 Kapitza Dirac Talbot Lau (KDTL) near-field experiment of Arndt's group. We show the region of the parameter space for each collapse model, which is excluded by these experiments. We show that matter-wave experiments provide model insensitive bounds, valid for a wide family of dissipative and non-markovian generalizations., Comment: 49 pages,16 figures

Mach-Zehnder Interferometrie mit wechselwirkenden Bose-Einstein Kondensaten in einem Doppel-Mulden-Potential Der Welle-Teilchen Dualismus erm��glicht die Konstruktion von Interferometern mit massiven Teilchen wie Elektronen, Neutronen, Atomen oder Molek��len. Die Atominterferometrie erfordert die Entwicklung von Komponenten analog zu den optischen Strahlteilern, Phasenschiebern, Kombinierern f��r die koh��rente bzw. phasenstabile Manipulation quantenmechanischer ��berlagerungszust��nde. W��hrend Atominterferometer urspr��nglich die Welleneigenschaften von der Materie untersucht haben, geh��ren sie heute zu den am weitesten entwickelten Pr��zisionsmessger��ten, die f��r technologische und fundamentale Fragestellungen verwendet werden. Bose-Einstein-Kondensate (BEK) aus ultrakalten atomaren Gasen stellen besondere Materiewellen dar: sie verf��gen ��ber eine kollektive Wellenfunktion und makroskopische Koh��renzeigenschaften. Dementsprechend werden Sie oft als Analog zu Laserlicht betrachtet und es stellt sich die Frage, ob BEKs einen ��hnlichen Entwicklungsschub f��r Materiewelleninterferometrie bewirken k��nnen wie einst der Laser f��r optische Interferometrie. Ein grundlegender Unterschied zwischen BEKs und Laserlicht stellen die atomaren Wechselwirkungen dar, welche zu einer intrinsischen Nichtlinearit��t f��hren. Auf der einen Seite f��hren atomare Wechselwirkungen zu Dekoh��renz und Dephasierung, die die Beobachtungszeit des Interferometers reduzieren. Auf der anderen Seite erm��glichen die Wechselwirkungen die Erzeugung nicht-klassischer (z. B. gequetschter) Zust��nde, welche die Sensitivit��t der BEK Interferometer ��ber das Schrotrausch-Limit hinaus verbessern k��nnen. In dieser Dissertation wurde experimentell ein Mach-Zehnder Interferometer f��r Bose- Einstein-Kondensate realisiert, welche auf einem Atomchip gefangen sind. Das Interferometer basiert auf der koh��renten Manipulation des BEKs in einem Doppel-Mulden- Potential. Es wurde insbesondere ein neuartiger Materiewellen-Kombinierer realisiert, das bisher fehlende Element in der Materiewellenoptik mit BEKs. Wir nutzten atomare Wechselwirkungen, um einen gequetschten Quantenzustand mit reduzierten Anzahl uktuationen zu realisieren, der gegen��ber dem Schrotrausch-Limit eine erh��hte Sensitivit��t aufweist. Mit Hilfe dieses Zustandes untersuchten wir die Phasendiusion, welche wiederum durch atomareWechselwirkungen erzeugt wird. Zum ersten Mal wurde auf eindeutiger Weise die Verbindung von Anzahl uktuationen und der Phasendiusion aufgezeigt. Die Verwendung eines gequetschten Zustandes erlaubte es uns, die Beobachtungszeit des Interferometers um mehr als das Doppelte zu verl��ngern. Dies stellt einen entscheidenden Schritt in Richtung BEK Interferometrie mit nichtklassischen Zust��nden dar und erweitert unser Verst��ndnis ��ber die Auswirkungen atomarer Wechselwirkungen in Vielteilchen-Quantensystemen. Die entwickelten Methoden sind geeignet, weitere komplexe Quantenzust��nde zu erzeugen und zu charakterisieren und es besteht die Honung, dass die atomaren Wechselwirkungen letztlich die Leistungsf��higkeit der Materiewelleninterferometrie verbessern k��nnen., Mach-Zehnder interferometry with interacting Bose-Einstein condensates in a double-well potential Particle-wave duality has enabled the construction of interferometers for massive particles such as electrons, neutrons, atoms or molecules. Implementing atom interferometry has required the development of analogues to the optical beam-splitters, phase shifters or recombiners to enable the coherent, i.e. phase-preserving manipulation of quantum superpositions. While initially demonstrating the wave nature of particles, atom interferometers have evolved into some of the most advanced devices for precision measurement, both for technological applications and tests of the fundamental laws of nature. Bose- Einstein condensates (BEC) of ultracold atoms are particular matter waves: they exhibit a collective many-body wave function and macroscopic coherence properties. As such, they have often been considered as an analogue to optical laser elds and it is natural to wonder whether BECs can provide to atom interferometry a similar boost as the laser brought to optical interferometry. One fundamental dierence between atomic BECs and lasers elds is the presence of atomic interactions, yielding an intrinsic non-linearity. On one hand, interactions can lead to eects destroying the phase coherence and limiting the interrogation time of trapped BEC interferometers. On the other hand, they can be used to generate nonclassical (e.g. squeezed) states to improve the sensitivity of interferometric measurements beyond the standard quantum limit (SQL). In this thesis, we present the realization of a full Mach-Zehnder interferometric sequence with trapped, interacting BECs con ned on an atom chip. Our interferometer relies on the coherent manipulation of a BEC in a magnetic double-well potential. For this purpose, we developed a novel type of matter-wave recombiner, an element which so far was missing in BEC atom optics. We have been able to exploit interactions to generate a squeezed atomic state with reduced atom number uctuations that could potentially yield a sensitivity improvement beyond the SQL. We used this state to study the interaction-induced diusion of the quantum phase. For the rst time we directly evidenced the link between fundamental atom number uncertainty and phase diusion, and demonstrated extended coherence times by the use of a non-classical state. This constitutes an important step towards the use of BECs for quantum-enhanced matter-wave interferometry and contributes to the understanding of interacting many-body quantum systems. It opens new possibilities for the generation, manipulation and detection of non-classical atomic states, and calls for further studies of the role of interactions as a resource for matter-wave interferometry.

The sensitivity of light and matter-wave interferometers to rotations is based on the Sagnac effect and increases with the area enclosed by the interferometer. In the case of light, the latter can be enlarged by forming multiple fibre loops, whereas the equivalent for matter-wave interferometers remains an experimental challenge. We present a concept for a multi-loop atom interferometer with a scalable area formed by light pulses. Our method will offer sensitivities as high as $2\cdot10^{-11}$ rad/s at 1 s in combination with the respective long-term stability as required for Earth rotation monitoring., Comment: 8 pages, 2 figures