Spatially resolved phase reconstruction for atom interferometry

Atom interferometers are employed for numerous purposes such as inertial sensing. They measure forces by encoding their signal in phase shifts between matter waves. Signal extraction algorithms typically require the resulting interference patterns to feature a priori known spatial distributions of intensity and phase. Deviations from these assumed spatial distributions, such as those caused by inhomogeneous laser wave fronts, can lead to systematic errors. For long interrogation times, such as for space operation, these distributions can display highly complex structures. We present an extraction algorithm designed for interference patterns featuring arbitrary and unknown temporally stable spatial phase profiles utilizing Principal Component Analysis. It characterizes complex phase profiles and thereby turns effects into a measured quantity which caused systematic errors in previous algorithms. We verify the algorithm’s accuracy and assess the statistical reconstruction error in the presence of atom projection noise as a function of the number of atoms and images. Finally, we extract the spatial phase profiles from experimental data obtained by an atom gravimeter

Twin-lattice atom interferometry

Inertial sensors based on cold atoms have great potential for navigation, geodesy, or fundamental physics. Similar to the Sagnac effect, their sensitivity increases with the space-time area enclosed by the interferometer. Here, we introduce twin-lattice atom interferometry exploiting Bose-Einstein condensates. Our method provides symmetric momentum transfer and large areas in palm-sized sensor heads with a performance similar to present meter-scale Sagnac devices

Multi-loop atomic Sagnac 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 $$2\times 10^{-11}$$ rad/s at 1 s in combination with the respective long-term stability as required for Earth rotation monitoring

A scalable, symmetric atom interferometer for infrasound gravitational wave detection

We propose a terrestrial detector for gravitational waves with frequencies between 0.3 and 5 Hz based on atom interferometry. As key elements, we discuss two symmetric matter-wave interferometers, the first one with a single loop and the second one featuring a folded triple-loop geometry. The latter eliminates the need for atomic ensembles at femtokelvin energies imposed by the Sagnac effect in other atom interferometric detectors. The folded triple-loop geometry also combines several advantages of current vertical and horizontal matter wave antennas and enhances the scalability in order to achieve a peak strain sensitivity of 2×10^(-21)/√(Hz)

A scalable, symmetric atom interferometer for infrasound gravitational wave detection

We propose a terrestrial detector for gravitational waves with frequencies between 0.3 and 5 Hz based on atom interferometry. As key elements, we discuss two symmetric matter-wave interferometers, the first one with a single loop and the second one featuring a folded triple-loop geometry. The latter eliminates the need for atomic ensembles at femtokelvin energies imposed by the Sagnac effect in other atom interferometric detectors. The folded triple-loop geometry also combines several advantages of current vertical and horizontal matter wave antennas and enhances the scalability in order to achieve a peak strain sensitivity of 2 x 10^{-21} Hz^{-1/2}

Optomechanical resonator-enhanced atom interferometry

Matter-wave interferometry and spectroscopy of optomechanical resonators offer complementary advantages. Interferometry with cold atoms is employed for accurate and long-term stable measurements, yet it is challenged by its dynamic range and cyclic acquisition. Spectroscopy of optomechanical resonators features continuous signals with large dynamic range, however it is generally subject to drifts. In this work, we combine the advantages of both devices. Measuring the motion of a mirror and matter waves interferometrically with respect to a joint reference allows us to operate an atomic gravimeter in a seismically noisy environment otherwise inhibiting readout of its phase. Our method is applicable to a variety of quantum sensors and shows large potential for improvements of both elements by quantum engineering. © 2020, The Author(s)

Atom-Chip Fountain Gravimeter

We demonstrate a quantum gravimeter by combining the advantages of an atom chip for the generation, delta-kick collimation, and coherent manipulation of freely falling Bose-Einstein condensates (BECs) with an innovative launch mechanism based on Bloch oscillations and double Bragg diffraction. Our high-contrast BEC interferometer realizes tens of milliseconds of free fall in a volume as little as a one centimeter cube and paves the way for measurements with sub-μGal accuracies in miniaturized, robust devices

Twin-lattice atom interferometry

Inertial sensors based on cold atoms have great potential for navigation, geodesy, or fundamental physics. Similar to the Sagnac effect, their sensitivity increases with the space-time area enclosed by the interferometer. Here, we introduce twin-lattice atom interferometry exploiting Bose-Einstein condensates of rubidium-87. Our method provides symmetric momentum transfer and large areas offering a perspective for future palm-sized sensor heads with sensitivities on par with present meter-scale Sagnac devices. Our theoretical model of the impact of beam splitters on the spatial coherence is highly instrumental for designing future sensors

QGyro : Schlussbericht zum Verbundvorhaben Quanten-Inertialsensorsystem (QGyro)

Das Verbundvorhaben QGyro (Quanten-Inertialsensorsystem) ist ein Teil der High-Tech-Strategie der Bundesregierung und erhält Finanzierung durch das Bundesministerium für Wirtschaft und Klimaschutz (BMWK) mit Unterstützung der Raumfahrtagentur am Deutschen Zentrum für Luft- und Raumfahrt DLR e.V. (Förderkennzeichen 50RK1957). Im Rahmen dieses Forschungsvorhabens wurden mithilfe der Quantentechnologie innovative Konzepte für die Navigation von Plattformen entwickelt. Das Hauptziel des Projekts ist die Untersuchung von Hybridansätzen zur Inertialsensorik, bei der Quantensensoren mit klassischen inertialen Messeinheiten miteinander kombiniert werden um Fehler in der Positionsbestimmung zu reduzieren. Ein Hauptaugenmerk lag auf der Entwicklung neuartiger Quantensensoren. Ein erster Ansatz war die Schaffung eines einachsigen, quantenbasierten Inertialsensors als Proof-of-Concept. Dies beinhaltet den Sensorkopf, aber auch die Perepherie, wie Lasersysteme und Elektronik. Darüber hinaus wurden Entwicklungen in Richtung von sechsachsigen quantenbasierten Intertialsensoren angestoßen und Realisierungskonzepte erarbeitet. Ein besonderer Fokus lag auf der Stabilisierung und aktiven Ausrichtung des entwickelten Messkopfes, was durch Simulationen und experimentelle Tests nachgewiesen werden konnte. Dies beinhaltete die Entwicklung eines Teststandes, die Erarbeitung eines Atom-StrapDown-Algorithmus zur Kombination von Quanten-Inertialsensoren und klassischer Inertialsensorik sowie die Umsetzung einer stabilisierten Plattform für den Sensorkopf. Die erfolgreiche Umsetzung wurde in enger Zusammenarbeit mit Forschungseinrichtungen an der Leibniz Universität Hannover (Institut für Erdmessung, Institut für Quantenoptik) sowie etablierten Unternehmen wie der iMAR GmbH erreicht. Das Projekt QGyro trägt dazu bei, die High-Tech-Strategie der Bundesregierung im Bereich der Quantentechnologie und Navigation voranzutreiben.The collaborative project QGyro (quantum inertial sensor system) is part of the German Federal Government’s High-Tech Strategy and receives funding from the German Federal Ministry of Economics and Climate Protection (BMWK) with support from the Space Agency at the German Aerospace Center DLR e.V. (funding code 50 RK 1957). This research project used quantum technology to develop innovative concepts for the navigation of kinematic platforms. The main goal of the project is to investigate hybrid approaches for inertial sensors, combining quantum technology with classical inertial measurement devices in order to reduce errors in positioning. A primary focus has been the development of novel quantum sensors. A first approach considered the creation of a single-axis, quantum-based inertial sensor as a proof-of-concept. This includes the sensor head, and also the peripherals, such as laser systems and electronics. Furthermore, developments towards a six-axis quantum-based inertial sensor were initiated and realization concepts were elaborated. Further focus was on the stabilization and active alignment of the developed sensing head. For this purpose, a stabilized platform was designed and built that can compensate linear accelerations during the measurement time of the quantum sensor. A so-called Atom Strapdown algorithm was designed and implemented for inertial navigation for the combination of quantum inertial sensors and classical inertial sensors. This algorithm has been tested, optimized and validated in extensive simulation studies. Moreover, a successful application of the algorithm to real data was achieved by emulating the CAI observations with a navigation-grade IMU during the generation of the hybrid scenario. Algorithms for determining the uncertainties of the atomic interferometer were further developed and validated on prototype measurement series. Successful implementation was achieved in close collaboration with research institutions at Leibniz Universität Hannover (Institute of Geodesy, Institute of Quantum Optics) as well as established companies such as iMAR GmbH. The QGyro project contributes to advancing the German government’s high-tech strategy in the field of quantum technology and navigation.Deutsche Raumfahrtagentur im Deutschen Zentrum für Luft- und Raumfahrt e.V./Systemuntersuchungen und Technologie für die Satellitennavigation/BMWK 50 RK 1957/E