We demonstrate a multiaxis atom interferometer based on a pyramidal magneto-optical trap and one diode laser. Being simple and capable of multiaxis operation, our atomic sensor opens up applications in geodesy, geology, or inertial navigation.
Atom interferometry has become one of the most powerful technologies for precision measurements. To develop simple, precise, and versatile atom interferometers for inertial sensing, we demonstrate an atom interferometer measuring acceleration, rotation, and inclination by pointing Raman beams toward individual faces of a pyramidal mirror. Only a single diode laser is used for all functions, including atom trapping, interferometry, and detection. Efficient Doppler-sensitive Raman transitions are achieved without the velocity selecting the atom sample, and with zero differential AC Stark shift between the cesium hyperfine ground states, increasing signal-to-noise and suppressing systematic effects. We measure gravity along two axes (vertical and 45∘ to the vertical), rotation, and inclination with sensitivities of 6μm/s2/Hz, 300μrad/s/Hz, and 4μrad/Hz, respectively. This work paves the way toward deployable multiaxis atom interferometers for geodesy, geology, or inertial navigation.
We demonstrate a scheme for atom interferometry to measure multiple axes of accelerations and rotations based on a single-diode laser and a pyramidal magneto-optical trap. The atom interferometer is constructed based on a simple and robust design. Additionally, with zeroed AC Stark shift, efficient Raman transition has been achieved by use of modest laser intensity and a small single photon detuning. By irradiating Raman beams toward not only the whole pyramid but also individual pyramidal faces, multiaxis atom interferometers have been operated. As a demonstration, the vertical interferometer measures the gravity with a sensitivity of 6 μm/s2 /√Hz and one interferometer along the diagonal axis observes the long-term tilt drift of the platform with a sensitivity of 4 μrad/√Hz. As a gyroscope, the atom interferometer along the diagonal axis achieves a sensitivity of 300 μrad/s/√Hz. This work paves the way toward compact, precise and multiaxis atom interferometers for geodesy, geology, or inertial navigation.
Inertial sensors based on cold atom interferometry exhibit many interesting features for applications related to inertial navigation, particularly in terms of sensitivity and long-term stability. However, at present the typical atom interferometer is still very much an experiment—consisting of a bulky, static apparatus with a limited dynamic range and high sensitivity to environmental effects. To be compliant with mobile applications further development is needed. In this work, we present a compact and mobile experiment, which we recently used to achieve the first inertial measurements with an atomic accelerometer onboard an aircraft. By integrating classical inertial sensors into our apparatus, we are able to operate the atomic sensor well beyond its standard operating range, corresponding to half of an interference fringe. We report atom-based acceleration measurements along both the horizontal and vertical axes of the aircraft with one-shot sensitivities of 2.3 × 10−4 g over a range of ∼ 0.1 g. The same technology can be used to develop cold-atom gyroscopes, which could surpass the best optical gyroscopes in terms of long-term sensitivity. Our apparatus was also designed to study multi-axis atom interferometry with the goal of realizing a full inertial measurement unit comprised of the three axes of acceleration and rotation. Finally, we present a compact and tunable laser system, which constitutes an essential part of any cold-atom-based sensor. The architecture of the laser is based on phase modulating a single fiber-optic laser diode, and can be tuned over a range of 1 GHz in less than 200 μs.
We show that light-pulse atom interferometry with atomic point sources and spatially resolved detection enables multiaxis (two rotation, one acceleration) precision inertial sensing at long interrogation times. Using this method, we demonstrate a light-pulse atom interferometer for 87Rb with 1.4 cm peak wave packet separation and a duration of 2T=2.3s. The inferred acceleration sensitivity of each shot is $6.7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}12}g$, which improves on previous limits by more than 2 orders of magnitude. We also measure Earth's rotation rate with a precision of 200nrad/s.
The use of matter-wave interferometry to detect inertial forces is already a powerful tool in precision measurement, but extending it beyond the lab to navigation applications requires optimization for compact setups. Here researchers characterize point-source atom interferometry (PSI) in a centimeter-scale cell, using an expanding cloud of cold atoms and an optical Raman interaction for simultaneous measurement of the system's acceleration along the Raman laser beams plus its rotation vector projected into the plane perpendicular to the beams. The sensitivity measurements presented here inform the further development of quantum inertial sensing that balances size and performance.
Recent laboratory experiments have demonstrated atom interference-based inertial force sensors operating at sensitivities near or exceeding the state-of-the-art [2x10-10 rad/sec/Hz1/2 (gyroscope), 10-9 g/Hz1/2 (accelerometer), and 10 E/Hz1/2 (gravity gradient, 1 E = 10-9 sec-2)]. Drawing on this recent experience, we seek to develop gravity gradient sensors which will provide unprecedented capabilities for navigation and geodesy applications. Our technical approach does not rely on cryogenic techniques, and should yield an instrument capable of operating on a broad array of platforms (eg. satellite, space station, plane, etc.). In the long run, we expect these instruments to be economical and robust The demonstration of Bose-Einstein condensation in dilute atomic vapors raises the prospect of a new class of de Broglie wave interferometric sensors. We have recently demonstrated a proof-of-principle accelerometer concept which exploits the novel coherence properties of Bose-Einstein condensed atomic sources.