The project "Future Gravity Field Satellite Missions" (FGM) was a logical consequence of two previous phases in Theme 2 "Observation of the System Earth from Space" in the BMBF/DFG (Federal Ministry of Education and Research/German Research Foundation) Research and Development Programme GEOTECHNOLOGIEN.

We report on the realization of a compact atomic Mach–Zehnder-type Sagnac interferometer of 13.7 cm length, which covers an area of 19 mm2 previously reported only for large thermal beam interferometers. According to Sagnac's formula, which holds for both light and atoms, the sensitivity for rotation rates increases linearly with the area enclosed by the interferometer. The use of cold atoms instead of thermal atoms enables miniaturization of Sagnac interferometers without sacrificing large areas. In comparison with thermal beams, slow atoms offer better matching of the initial beam velocity and the velocity with which the matter waves separate. In our case, the area is spanned by a cold atomic beam of 2.79 m s−1, which is split, deflected and combined by driving a Raman transition between the two hyperfine ground states of 87Rb in three spatially separated light zones. The use of cold atoms requires a precise angular alignment and high wave front quality of the three independent light zones over the cloud envelope. We present a procedure for mutually aligning the beam splitters at the microradian level by making use of the atom interferometer itself in different configurations. With this method, we currently achieve a sensitivity of .

In the paper the authors present an atomic gyroscope for the precise measurement of rotations based on optical Raman transitions for the coherent beam splitting process. Two interferometers with overlapping counter propagating atomic trajectories are used to distinguish between rotation and acceleration. Furthermore, we report on the present status of the apparatus including the analysis of systematic effects, which lead to the current limitation of the sensor. Finally, future improvements based on the provided analysis of the sensor will be discussed.

We report on the phase-locking of two diode lasers based on self-seeded tapered amplifiers. In these lasers, a reduction of linewidth is achieved using narrow-band high-transmission interference filters for frequency selection. The lasers combine a compact design with a Lorentzian linewidth below 200 kHz at an output power of 300 mW for a wavelength of 780 nm. We characterize the phase noise of the phase-locked laser system and study its potential for coherent beam-splitting in atom interferometers.

We report on our compact transportable cold atom inertial sensor for precision sensing of rotations. The sensor consists of a dual Mach-Zehnder type atom interferometer operating with laser-cooled 87Rb. Raman processes are employed to coherently manipulate the matter waves. We present the latest inertial sensitive interferometer measurements and discuss the road map to reach the full potential of the sensor featuring a sensitivity of a few nrad/s/radic(Hz).

We present a compact and transportable inertial sensor forprecision sensing of rotations and accelerations. The sensor consistsof a dual atom interferometer operated with laser-cooled 87Rb.Raman processes are employed to coherently manipulate the matterwaves. We describe and characterize the experimental apparatus. Amethod for passing from a compact geometry to an extendedinterferometer with three independent atom-light interaction zones isproposed and investigated. The extended geometry will enhance thesensitivity by more than two orders of magnitude which is necessaryto achieve sensitivities better than 10-8rad/s/\(\sqrt{\rmHz}\).

The status of the dual atom interferometer for the precise measurement of inertial forces, based on optical Raman transitions for the coherent beam splitting process is reported. Two interferometers with overlapping counter propagating atomic trajectories are used to exactly distinguish between rotation and acceleration.

In response to ESA’s Call for proposals of 5 March 2007 of the COSMIC VISION 2015–2025 plan of the ESA science programme, we propose a M-class satellite mission to test of the Equivalence Principle in the quantum domain by investigating the extended free fall of matter waves instead of macroscopic bodies as in the case of GAUGE, MICROSCOPE or STEP. The satellite, called Matter Wave Explorer of Gravity, will carry an experiment to test gravity, namely the measurement of the equal rate of free fall with various isotopes of distinct atomic species with precision cold atom interferometry in the vicinity of the earth. This will allow for a first quantum test the Equivalence Principle with spin polarised particles and with pure fermionic and bosonic atomic ensembles. Due to the space conditions, the free fall of Rubidium and Potassium isotopes will be compared with a maximum accelerational sensitivity of 5·10 − 16 m/s2 corresponding to an accuracy of the test of the Equivalence Principle of 1 part in 1016. Besides the primary scientific goal, the quantum test of the Equivalence Principle, the mission can be extended to provide additional information about the gravitational field of the earth or for testing theories of fundamental processes of decoherence which are investigated by various theory groups in the context of quantum gravity phenomenology. In this proposal we present in detail the mission objectives and the technical aspects of the proposed mission.

We report the first implementation of a Gauss sum factorization algorithm by an internal state Ramsey interferometer using cold atoms. A sequence of appropriately designed light pulses interacts with an ensemble of cold rubidium atoms. The final population in the involved atomic levels determines a Gauss sum. With this technique we factor the number N=263193.

Summary form only given. The very high sensitivity of matter-wave interferometry for detecting accelerations and rotations has made it to an ideal tool for applications in fundamental physics and metrology. We report on the status of our dual atom interferometer for the precise determination of inertial forces. The aim is to investigate different interferometer pulse sequences, and measurements strategies like continuous or pulsed operation. In this project we use the synchronous operation of two counterpropagating atom interferometers to discriminate between accelerations and rotations. The ensembles of 10 muk cold 87 Rb atoms are launched with a velocity of about 4.4m/s from two double-mot sources on precisely controlled parabolas into the interferometer chamber. After the preparation of the atoms in the groundstate, a sequence of three atom-light interactions follows in the interferometry chamber forming the actual interferometer by coherently splitting, deflecting and recombining the atoms. These manipulations have been realized with optical Raman transitions. The detection is realized by measuring the fluorescence light in both output states in each interferometer. All this allows for a compact and transportable setup while still enabling sensitivities comparable to the best conventional sensors. In the current low resolution mode, we optimize critical interferometer components such as atom preparation and detection and analyze systematic effects.Finally the scheme to upgrade the experiment to the full sensitivity of 2*10 -9 rad/s for 1*10 8 atoms per shot at a velocity of 3m/s was presented.

The authors report on the status of our dual atom interferometer for the precise determination of inertial forces. The aim is to reveal the quantum limits of such an inertial sensor as well as to assess and to optimise measurement strategies like continuous or periodic operation modes.

We present and investigate different external cavity diode laser (ECDL) configurations for the manipulation of neutral atoms, wavelength-stabilized by a narrow-band high transmission interference filter. A novel diode laser, providing high output power of more than 1W, with a linewidth of less than 85kHz, based on a self-seeded tapered amplifier chip has been developed. Additionally, we compare the optical and spectral properties of two laser systems based on common laser diodes, differing in their coating, as well as one, based on a distributed-feedback (DFB) diode. The linear cavity setup in all these systems combines a robust and compact design with a high wavelength tunability and an improved stability of the optical feedback compared to diode laser setups using diffraction gratings for wavelength discrimination.

We present a compact Rb-87 atomic source for high precision dual atom interferometers. The source is based on a double-stage magneto-optical trap (MOT) design, consisting of a two-dimensional (2D) -MOT for efficient loading of a 3D-MOT. The accumulated atoms are precisely launched in a horizontal moving molasses. Our source generates a high atomic flux (>10(10) atoms/s) with precise and flexibly tunable atomic trajectories as required for high resolution Sagnac atom interferometry. We characterize the performance of the source with respect to the relevant parameters of the launched atoms, i.e., temperature, absolute velocity, and pointing, by utilizing time-of-flight techniques and velocity selective Raman transitions.

In this proceeding we present ongoing projects concerning high resolution measurements developed for future space missions based on ultracold atoms at the Institut ffir Quantenoptik (IQ) of the Leibniz-Universitdt Hannover. This work involves the realization of a Bose Einstein condensate in microgravitational environment and an inertial atomic quantum sensor.

In this article we present actual projects concerning high resolution measurements developed for future space missions based on ultracold atoms at the Institut für Quantenoptik (IQ) of the University of Hannover. This work involves the realization of a Bose–Einstein condensate in a microgravitational environment and of an inertial atomic quantum sensor.

In this paper, a concept for an atom interferometer for measurements of rotations and accelerations with very high sensitivity based on laser cooled rubidium atoms (CASI: cold atom Sagnac interferometer) and its experimental realisation are discussed. The aim is to reveal the quantum limits of such an inertial sensor as well as to assess and to optimise measurement strategies like continuous or periodic operation modes.