Detecting inertial effects with airborne matter-wave interferometry
Rémi Geiger, Vincent Ménoret, Guillaume Stern, Nassim Zahzam, Patrick Cheinet, Baptiste Battelier, André Villing, F. Moron, M. Lours, Yannick Bidel, Alexandre Bresson, Arnaud Landragin, Philippe Bouyer
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.
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.
Matter-wave inertial sensing relies on the capability of manipulating the coherent wave nature of matter to build an interferometer and accurately measure a phase difference. Since the massive particle associated to the matter wave senses inertial effects, the interferometer represents an accurate inertial probe. Atom interferometers have benefited from the outstanding developments of laser-cooling techniques and reached accuracies comparable to those of inertial sensors based on optical interferometry. Thanks to their long term stability, they offer a breakthrough advance in accelerometry, gyroscopy and gravimetry, for applications to inertial guidance, geoid determinations, geophysics and metrology. They are also excellent candidates for laboratory-based tests of general relativity that could compete with the current tests using astronomical or macroscopic bodies. For example, they may provide new answers to the question of whether the free fall acceleration of a particle is universal, i.e. independent of its internal composition and quantum properties. We report here the first operation of an airborne quantum inertial sensor. We highlight their promising applications to inertial navigation and Earth observation. We also describe the improvement of the quantum sensor sensitivity in weightlessness, and discuss the possibility to conduct airborne or spaceborne tests of the Universality of Free Fall with quantum objects. We finally describe a matter-wave laser based interferometric gravitational antenna (MIGA). This infrastructure will allow for measuring with unprecedented resolution variations of the Earths gravity and of the strain of space-time allowing for enhancing the capabilities of existing and future gravitational wave detectors.
Quantum technology based on cold-atom interferometers is showing great promise for fields such as inertial sensing and fundamental physics. However, the best precision achievable on Earth is limited by the free-fall time of the atoms, and their full potential can only be realized in Space where interrogation times of many seconds will lead to unprecedented sensitivity. Various mission scenarios are presently being pursued, which plan to implement matter-waves inertial sensors to detect gravitational waves, to measure the Earth gravity field or to test fundamental physics such as the Equivalence Principle.We developed a cold atom sensor experiment adapted to microgravity platforms, especially the ZERO-G plane. To achieve a test of the Universality of Free Fall, we realize the first onboard operation of simultaneous ^{87}Rb - ^{39}K interferometers in the weightlessness environment produced during parabolic flight. The large vibration levels (10 ^{-2} g/Hz ^{1/2}), acceleration range and rotation rates (5 deg/s) during flight present significant technical challenges for atom interferometers. By hybridizing each atomic sensor with a common mechanical accelerometer, we achieve a sensitivity of 3.4 10 ^{-5} g per shot-more than 1600 times below the ambient vibration level onboard the aircraft. We demonstrate the capability of our dual-quantum sensor by measuring the Eötvös parameter with systematic-limited uncertainties of 3.0 10 ^{-4} during micro-gravity. This constitutes the first quantum test of the equivalence principle in a free falling vehicle. Our results can be extended to the trajectory of a satellite for future Space missions. We also achieved a simultaneous ^{87}Rb- ^{39}K interferometer on ground with a long term stability on the differential acceleration measurement around 5 10 ^{-8}g, limited by the fall of the atom clouds. To increase the interrogation time and the sensitivity, a ZERO-G simulator has been installed in our laboratory and allows our experiment to be in free fall during 500 ms every 12 seconds, to achieve highly repeatable measurements in microgravity. We expect to increase our short-term sensitivity by two orders of magnitude, and consequently reach a long-term measurement of the Eötvös parameter at the level of 10 ^{-11}.To benefit from the free fall of the experiment completely, it is necessary to produce atoms clouds with a reduced velocity dispersion. To reach this goal, we put ^{87}Rb atoms in an optical dipole trap supplied by a compact fiber laser compliant with onboard applications and decrease the optical power on a very controlled way to obtain evaporative cooling. Preliminary results of ultra-fast evaporative cooling (less than a few seconds) onboard the ZERO-G plane allowed us to reach a regime of temperature compliant with an interrogation time of the order of one second. This method and technology will be tested on the ZERO-G simulator as well.
Matter-wave interferometry has enabled high precision measurements of inertial forces such as gravity and the Coriolis force. This is facilitated by the long-term stability of the physical properties of atoms and lasers. Recent experiments have demonstrated the operation of portable, robust sensors using atom interferometry. This has potential uses in the context of inertial navigation, where conventional devices suffer from long-term drifts due to bias instability. Furthermore, determining position via dead reckoning requires minimisation of dead time between measurements. This thesis presents the development of an atom interferometer for measuring horizontal accelerations. In this configuration, gravity induces motion across the laser wavefront, which constrains the tolerable level of wavefront distortions. Effective control of the experiment allows the interferometer to be operated at a rate of 4 Hz. A cold ensemble of 10^6 atoms in the same internal state is prepared in 150 ms. The interferometer operates using a sequence of three laser pulses separated by T= 25 ms to achieve sensitivity to horizontal accelerations. Combining this with a classical accelerometer provides a method of correcting for vibration-induced noise, as well as determining the interferometer fringe order. After an integration time of 40 s, the sensitivity to horizontal accelerations is better than 3^-6 m s^-2. Effects which limit this sensitivity are discussed.
Atom interferometry has hugely benefitted from advances made in cold atom physics over the past twenty years, and ultra-precise quantum sensors are now available for a wide range of applications [1]. In particular, cold atom interferometers have shown excellent performances in the field of acceleration and rotation measurements [2,3], and are foreseen as promising candidates for navigation, geophysics, geo-prospecting and tests of fundamental physics such as the Universality of Free Fall (UFF). In order to carry out a test of the UFF with atoms as test masses, one needs to compare precisely the accelerations of two atoms with different masses as they fall in the Earth’s gravitational field. The sensitivity of atom interferometers scales like the square of the time during which the atoms are in free fall, and on ground this interrogation time is limited by the size of the experimental setup to a fraction of a second. Sending an atom interferometer in space would allow for several seconds of excellent free-fall conditions, and tests of the UFF could be carried out with precisions as low as 10-15 [4]. However, cold atoms experiments rely on complex laser systems, which are needed to cool down and manipulate the atoms, and these systems are usually very sensitive to temperature fluctuations and vibrations. In addition, when operating an inertial sensor, vibrations are a major issue, as they deteriorate the performances of the instrument. This is why cold atom interferometers are usually used in ground based facilities, which provide stable enough environments. In order to carry out airborne or space-borne measurements, one has to design an instrument which is both compact and stable, and such that vibrations induced by the platform will not deteriorate the sensitivity of the sensor. We report on the operation of an atom interferometer on board a plane carrying out parabolic flights (Airbus A300 Zero-G, operated by Novespace). We have constructed a compact and stable laser setup, which is well suited for onboard applications. Our goal is to implement a dual-species Rb-K atom interferometer in order to carry out a test of the UFF in the plane. In this perspective, we are designing a dual-wavelength laser source, which will enable us to cool down and coherently manipulate the quantum states of both atoms. We have successfully tested a preliminary version of the source and obtained a double species magneto-optical trap (MOT).
Very Long Baseline Atom Interferometry (VLBAI) corresponds to ground-based atomic matter-wave interferometry on large scales in space and time, letting the atomic wave functions interfere after free evolution times of several seconds or wave packet separation at the scale of meters. As inertial sensors, e.g., accelerometers, these devices take advantage of the quadratic scaling of the leading order phase shift with the free evolution time to enhance their sensitivity, giving rise to compelling experiments. With shot noise-limited instabilities better than 10−9 m/s2 at 1 s at the horizon, VLBAI may compete with state-of-the-art superconducting gravimeters, while providing absolute instead of relative measurements. When operated with several atomic states, isotopes, or species simultaneously, tests of the universality of free fall at a level of parts in 1013 and beyond are in reach. Finally, the large spatial extent of the interferometer allows one to probe the limits of coherence at macroscopic scales as well as the interplay of quantum mechanics and gravity. We report on the status of the VLBAI facility, its key features, and future prospects in fundamental science.
Inertial sensors based on cold atoms and light-pulse interferometry exhibit state-of-the-art sensitivity and ultra-low measurement bias that could revolutionize a variety of fields including geophysics and seismology, gravitational wave detection and fundamental tests of gravity, and inertial navigation. In the latter case, cold-atom interferometers are widely considered as breakthrough technology for future autonomous INSs. Nowadays, absolute quantum inertial sensors are available as commercial and field-deployable devices. Yet, their current size and complexity has not yet reached a technology readiness level compatible with mobile applications or plug-and-play operation by non-specialists. These systems are in desperate need of further development and miniaturization. We will present progress beyond these first experiments while exploring new methods relying on 3D matter-wave manipulation that can lead to interferometer geometries that are simultaneously sensitive to accelerations and rotations in 3D and can discern their vector components within a single measurement. These novel innovations produce additional sensitivity to rotations and gravity gradients which has not yet been exploited experimentally and could be a game changing innovation for future atomic sensors. The ability to measure the full acceleration and rotation vectors with a compact, high-precision, low-bias inertial sensor could strongly impact the fields of inertial navigation, gravity gradiometry, and gyroscopy.