The techniques of laser cooling combined with atom interferometry make possible the realization of very sensitive and accurate inertial sensors like gyroscopes or accelerometers. Besides earth-based developments, the use of these techniques in space should provide extremely high sensitivity for research in fundamental physics, Earth's observation and exploration of the solar system.
The techniques of laser cooling combined with atom interferometry make possible the realization of very sensitive and accurate inertial sensors like gyroscopes or accelerometers. Besides earth-based developments, the use of these techniques in space should provide extremely high sensitivity for research in fundamental physics, Earth's observation and exploration of the solar system.
The remarkable success of atom coherent manipulation techniques has motivated competitive research and development in precision metrology. Matter-wave inertial sensors – accelerometers, gyrometers, gravimeters – based on these techniques are all at the forefront of their respective measurement classes. Atom inertial sensors provide nowadays about the best accelerometers and gravimeters and allow, for instance, to make the most precise monitoring of gravity or to device precise tests of the weak equivalence principle (WEP). I present here some recent advances in these fields.
Current sensors used for inertial navigation are based on technology with inherent sensitivity limitations. Atom interferometry is a very promising replacement, which could yield many orders of magnitude of improvement in sensitivity, leading to more accurate navigation over longer periods of time relative to current technology. This research investigates the physics of atom interferometry through the construction and characterization of an atomic accelerometer/gyroscope combination. In contrast to current state-of-the-art atomic sensors, which use pulsed cold atom sources and pulsed laser beams, the apparatus investigated relies purely on continuous atomic and laser beams. These differences would result in a sensor that lends itself more readily to smaller sizing, lower power consumption, and reduced complexity. This change in approach to atomic interferometry also introduces challenges resulting from laser and atomic beam divergences and the velocity averaging due to both longitudinal and transverse temperature, which this dissertation shows how to overcome. The work contained herein explores many stages of construction of an atomic gyro including the demonstration and characterization of two-dimensional laser cooling of atoms, stimulated Raman transitions, and Ramsey and spin echo interference. The implications for future research are also outlined and discussed.
Inertial sensors relying on atom interferometry offer a breakthrough advance in a variety of applications, such as inertial navigation, gravimetry or ground- and space-based tests of fundamental physics. These instruments require a quiet environment to reach their performance and using them outside the laboratory remains a challenge. Here we report the first operation of an airborne matter-wave accelerometer set up aboard a 0g plane and operating during the standard gravity (1g) and microgravity (0g) phases of the flight. At 1g, the sensor can detect inertial effects more than 300 times weaker than the typical acceleration fluctuations of the aircraft. We describe the improvement of the interferometer sensitivity in 0g, which reaches 2 x 10-4 ms-2 / √Hz with our current setup. We finally discuss the extension of our method to airborne and spaceborne tests of the Universality of free fall with matter waves. Inertial sensors using atom interferometry have applications in geophysics, navigation- and space-based tests of fundamental physics. Here, the first operation of an atom accelerometer during parabolic flights is reported, demonstrating high-resolution measurements at both 1g and 0g.
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.
The remarkable success of atom coherent manipulation techniques has motivated competitive research and development in precision metrology. Matter-wave inertial sensors – accelerometers, gyrometers, gravimeters – based on these techniques are all at the forefront of their respective measurement classes. Atom inertial sensors provide nowadays about the best accelerometers and gravimeters and allow, for instance, to make the most precise monitoring of gravity. New concepts of matter-wave interferometry can also be used to study the low frequency variations of the strain tensor of space-time and gravitation. For instance, the MIGA instrument, which is currently built in the underground laboratory in Rustrel, France will allow the monitoring of the evolution of the gravitational field at unprecedented sensitivity, which will be exploited both for geophysical studies and for Gravitational Waves (GWs) observations. This present will present the status of this instrument.
This report assesses the potential of gyroscopes and accelerometers based on cold atom interferometry (CAI) for space and defence applications, by analysing their strengths and weaknesses in comparison with devices based on other working principles. Indeed, it is widely recognized that quantum sensors based on atomic interferometry provide absolute measurements with the potential for high sensitivity and long-term stability. This last property is particularly valuable for accelerometers and gyroscopes to be used for inertial navigation, since it guarantees precise positioning without the need for frequent recalibrations, a shortcoming which affects several devices presently in use. \nHigh-performance inertial sensors play an important role both in space applications, where gyroscopes are widely used e.g. to orientate a satellite and its on-board communications and sensing equipment, and in defence, where gyroscopes and accelerometers constitute the core of the inertial measurement units to be used for autonomous navigation, e.g. in GNSS-denied conditions. The EU has a well-established role in space with the Copernicus and Galileo programmes, and a fledging but increasing involvement in the defence industry. An independent assessment of a quantum technology such as cold atom interferometry which may in time acquire a significant role in these fields is a precondition to advance well-grounded suggestions for EU policy initiatives.