Advances in Atom Interferometry and their Impacts on the Performance of Quantum Accelerometers On-board Future Satellite Gravity Missions
Alireza HosseiniArani, Manuel Schilling, Quentin Beaufils, Annike Knabe, Benjamin Tennstedt, Alexey Kupriyanov, Steffen Schön, Franck Pereira dos Santos, Jürgen Müller
Recent advances in cold atom interferometry have cleared the path for space applications of quantum inertial sensors, whose level of stability is expected to increase dramatically with the longer interrogation times accessible in space. In this study, an in-orbit model is developed for a Mach-Zehnder-type cold-atom accelerometer. Performance tests are realized under different assumptions about the positioning and rotation compensation method, and the impact of various sources of errors on instrument stability is evaluated. Current and future advances for space-based atom interferometry are discussed, and their impact on the performance of quantum sensors on-board satellite gravity missions is investigated in three different scenarios: state-of-the-art scenario(expected to be ready to launch in 5 years), near-future (expected to be launched in the next 10 to 15 years)and far-future scenarios (expected for the next 20 to 25 years). Our results indicate that the highest sensitivity is achievable by positioning the electrostatic accelerometer at the center of mass of the satellite and the quantum accelerometer aside, on the cross-track axis of the satellite. We show that one can achieve a sensitivity level close to 5×10-10m/s2/Hz with the current state-of-the-art technology. We also estimate that in the near and far-future, atom interferometry in space is expected to achieve sensitivity levels of 1×10-11m/s2/Hz and 1×10-12m/s2/Hz, respectively. A roadmap for improvements in atom interferometry is provided that would maximize the performance of future quantum accelerometers, considering their technical capabilities. Finally, the possibility and challenges of having ultra-sensitive atom interferometry in space for future space missions are discussed.
Recent advances in cold atom interferometry have cleared the path for space applications of quantum inertial sensors, whose level of stability is expected to increase dramatically with the longer interrogation times accessible in space. In this study, an in-orbit model is developed for a Mach-Zehnder-type cold-atom accelerometer. Performance tests are realized under different assumptions about the positioning and rotation compensation method, and the impact of various sources of errors on instrument stability is evaluated. Current and future advances for space-based atom interferometry are discussed, and their impact on the performance of quantum sensors on-board satellite gravity missions is investigated in three different scenarios: state-of-the-art scenario(expected to be ready to launch in 5 years), near-future (expected to be launched in the next 10 to 15 years)and far-future scenarios (expected for the next 20 to 25 years). Our results indicate that the highest sensitivity is achievable by positioning the electrostatic accelerometer at the center of mass of the satellite and the quantum accelerometer aside, on the cross-track axis of the satellite. We show that one can achieve a sensitivity level close to 5×10-10m/s2/Hz with the current state-of-the-art technology. We also estimate that in the near and far-future, atom interferometry in space is expected to achieve sensitivity levels of 1×10-11m/s2/Hz and 1×10-12m/s2/Hz, respectively. A roadmap for improvements in atom interferometry is provided that would maximize the performance of future quantum accelerometers, considering their technical capabilities. Finally, the possibility and challenges of having ultra-sensitive atom interferometry in space for future space missions are discussed.
In recent years, quantum technology has attracted attention in inertial navigation, especially due to its extreme sensitivity to inertial forces and strong immunity to drifts, which plague conventional sensors. There are multiple groups around the world working on cold atom interferometry aiming to develop high sensitive inertial sensors for very high accuracy autonomous navigation. Recent advancements in micro-fabrication technologies have helped in development of robust and miniaturized atom interferometry based high performance inertial systems. These, in future, will pave way for autonomous satellite inertial navigation sensors based on cold atoms. Here we discuss the achievements towards realizing cold atom inertial sensors and their indomitable role as inertial sensors for future satellites. A detailed survey on the initiatives taken by different space agencies, their achievements and their plans to explore its potential in space are also discussed.
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.
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.
This report provides an assessment on cold atom interferometry (CAI) gravity sensing for Earth Observation (EO), and is intended as an instrument to facilitate the interactions between the different communities involved in the definition of a related satellite mission. Indeed, the definition of the objectives of future gravity missions and of the technologies needed for their implementation is the result of complex negotiations and compromises: geodesy and geophysics researchers detail the scientific requirements dictated by their investigation areas (e.g. solid Earth dynamics, ocean mass and heat transport, ice sheets and glaciers evolution), policymakers express their concerns and their priorities (e.g. natural hazards risk assessment, ground water monitoring, floods and droughts forecast), engineers and technology experts devise and implement the most suitable techniques to actually build the satellite and its gravity sensing payload. \nAs we will show in this report, the scientific consensus is that the scientific objectives of a next generation gravity mission (NGGM) to be deployed within a ~10 year timeframe can be achieved by upgrading established technologies already used in gravity-measuring satellites. Transformative technologies such as CAI-based gravity sensors leveraging Bose Einstein Condensates (BEC) of ultra-cold atoms may come to play a role in the longer term, provided that several technology challenges are overcome; in addition, further interdisciplinary work and the simulation of detailed mission scenarios are needed to fully establish their actual usefulness with regards to the attainment of future gravity missions scientific objectives.\nThe scientific community seems to agree on the opportunity of an intermediate stepping stone, which could take the form of a scientific mission with a dedicated satellite, in order to test and prove the in-space feasibility and the actual usefulness of CAI-based gravity sensors.
This report describes the physical principles underpinning cold atom interferometry (CAI) and shows how they can be leveraged to develop high-performance inertial and gravity sensors; the distinguishing properties and the maturity level of such sensors will also be assessed. \nProof-of-principles demonstrations have been made for CAI-based accelerometers and gyroscopes, which can enable long-term autonomous navigation and precise positioning for ships, submarines, and satellites. CAI-based gravimeters and gravity gradiometers have been developed and are being tested on the ground; satellite-based systems could in the future be used to monitor the Earth gravity field. This would allow a better understanding of several geophysical and climate phenomena which require long-term policies solidly supported by data. \nQuantum sensors based on cold atom interferometry may therefore impact existing and future EU programmes on space, defence, and Earth observation. This report provides background knowledge of the field to a non-specialist audience, and in particular to EU policymakers involved in technology support and potential applications.
Rotations play a detrimental role in achieving ultra-high-performance inertial measurements with an atom interferometer, leading potentially to a total loss of interference contrast and the emergence of dominant phase shift biases. This becomes particularly significant when considering operation in dynamic conditions such as those encountered in Earth orbiting satellites in the perspective of future space gravity missions on-boarding a cold atom accelerometer. We study in this context the impact of rotation on the phase shift and contrast of an atom interferometer and investigate mitigation strategies. An analytical model is derived and compared to experimental demonstrations carried out using an original setup in which the well-controlled proof-mass of a space electrostatic accelerometer is used as the retro-reflection mirror of a cold atom gravimeter. By properly counter-rotating the electrostatic proof-mass, we demonstrate for instance the possibility of recovering the interferometer contrast, otherwise equal to zero, to a level better than 90%, in both cases of constant angular velocities or in presence of angular accelerations. Our results demonstrate the possibility to perform high performance inertial measurements with a cold atom interferometer in a challenging environments.