The Cold Atom Laboratory is a multipurpose ultracold gas experiment currently being developed for operation on the international space station. It will have the ability to demonstrate proof-of-principle atom interferometry experiments in space. By using microgravity, atom interferometry has the potential to achieve extremely good performance in sensing and navigation applications. Terrestrial experiments can be used to explore potential challenges and prior to launch. One issue of concern is the release of cold atoms from a magnetic trap into free space. Although the atoms will not fall, they can acquire relatively large velocities due to technical limitations such as stray magnetic fields. This can limit the time available for measurements and thus the atom interferometer performance.
The Cold Atom Laboratory is a multipurpose ultracold gas experiment currently being developed for operation on the international space station. It will have the ability to demonstrate proof-of-principle atom interferometry experiments in space. By using microgravity, atom interferometry has the potential to achieve extremely good performance in sensing and navigation applications. Terrestrial experiments can be used to explore potential challenges and prior to launch. One issue of concern is the release of cold atoms from a magnetic trap into free space. Although the atoms will not fall, they can acquire relatively large velocities due to technical limitations such as stray magnetic fields. This can limit the time available for measurements and thus the atom interferometer performance.
Abstract Microgravity eases several constraints limiting experiments with ultracold and condensed atoms on ground. It enables extended times of flight without suspension and eliminates the gravitational sag for trapped atoms. These advantages motivated numerous initiatives to adapt and operate experimental setups on microgravity platforms. We describe the design of the payload, motivations for design choices, and capabilities of the Bose-Einstein Condensate and Cold Atom Laboratory (BECCAL), a NASA-DLR collaboration. BECCAL builds on the heritage of previous devices operated in microgravity, features rubidium and potassium, multiple options for magnetic and optical trapping, different methods for coherent manipulation, and will offer new perspectives for experiments on quantum optics, atom optics, and atom interferometry in the unique microgravity environment on board the International Space Station.
Owing to the low-gravity conditions in space, space-borne laboratories enable experiments with extended free-fall times. Because Bose–Einstein condensates have an extremely low expansion energy, space-borne atom interferometers based on Bose–Einstein condensation have the potential to have much greater sensitivity to inertial forces than do similar ground-based interferometers. On 23 January 2017, as part of the sounding-rocket mission MAIUS- 1, we created Bose–Einstein condensates in space and conducted 110 experiments central to matter-wave interferometry, including laser cooling and trapping of atoms in the presence of the large accelerations experienced during launch. Here we report on experiments conducted during the six minutes of in-space flight in which we studied the phase transition from a thermal ensemble to a Bose–Einstein condensate and the collective dynamics of the resulting condensate. Our results provide insights into conducting cold-atom experiments in space, such as precision interferometry, and pave the way to miniaturizing cold-atom and photon-based quantum information concepts for satellite-based implementation. In addition, space-borne Bose–Einstein condensation opens up the possibility of quantum gas experiments in low-gravity conditions1,2.
Ultra-cold quantum gases in space promise to boost the sensitivity of matter-wave interferometers. Applications of the latter extend from fundamental physics over the use in navigation to interdisciplinary applications such as geodesy, e.g. satellite gravimetry [1, 2]. Exploiting quantum gases for high-precision interferometry places high demands on their control and manipulation. We take benefit of various microgravity platforms such as the Bremen drop tower [3], the Einstein elevator in Hannover [4], sounding rockets [5,6] and the international space station [7] to advance the necessary methods. The DLR-mission MAIUS-1 demonstrated Bose-Einstein condensation and performed first interferometry experiments [4]. NASA’s Cold Atom Laboratory continues this research in orbit on the ISS [7]. In addition, atom interferometry is pursued in highly dynamic environments such as parabolic flights [8]. Starting from a rubidium Bose-Einstein condensate, recently lowest expansion energies have been achieved by us in the Bremen drop tower as required for extending atom interferometry over several seconds [9]. Extending these methods to quantum mixtures not only opens up new physics in the absence of buoyancy, but also faces challenges regarding their use for interferometry. Interferometers based on two chemical elements have been proposed for quantum tests of the equivalence principle on the ISS as well as on satellites. Currently we prepare a sounding rocket mission to investigate the simultaneous generation and manipulation of potassium and rubidium condensates [10]. Together with CAL [7], these experiments will prepare the DLR-NASA multi-user facility BECCAL for research on quantum gas mixtures and interferometry [11] as well as enhance the readiness level of methods required for STE-QUEST [12], a proposal for a satellite mission currently studied in an modified version within ESA’s VOYAGE 2050 program [13].
Ultracold atomic gases hold unique promise for space science by capitalizing on quantum advantages and extended freefall, afforded in a microgravity environment, to enable next-generation precision sensors. Atom interferometers are a class of quantum sensors which can use freely falling gases of atoms cooled to sub-photon-recoil temperatures to provide unprecedented sensitivities to accelerations, rotations, and gravitational forces, and are currently being developed for space-based applications in gravitational, earth, and planetary sciences, as well as to search for subtle forces that could signify physics beyond General Relativity and the Standard Model. NASA's Cold Atom Lab (CAL) operates onboard the International Space Station as a multi-user facility for studies of ultracold atoms and to mature quantum technologies, including atom interferometry, in persistent microgravity. In this paper, we report on path-finding experiments utilizing ultracold 87Rb atoms in the CAL atom interferometer, which was enabled by an on-orbit upgrade of the CAL science module: A three-pulse Mach-Zehnder interferometer was studied to understand limitations from the influence of ISS vibrations. Additionally, Ramsey shear-wave interferometry was used to manifest interference patterns in a single run that were observable for over 150 ms free-expansion time. Finally, the CAL atom interferometer was used to remotely measure the photon recoil from the atom interferometer laser as a demonstration of the first quantum sensor using matter-wave interferometry in space.
Deployment of ultracold atom interferometers (AI) into space will capitalize on quantum advantages and the extended freefall of persistent microgravity to provide high-precision measurement capabilities for gravitational, Earth, and planetary sciences, and to enable searches for subtle forces signifying physics beyond General Relativity and the Standard Model. NASA’s Cold Atom Lab (CAL) operates onboard the International Space Station as a multi-user facility for fundamental studies of ultracold atoms and to mature space-based quantum technologies. We report on pathfinding experiments utilizing ultracold 87Rb atoms in the CAL AI. A three-pulse Mach–Zehnder interferometer was studied to understand the influence of ISS vibrations. Additionally, Ramsey shear-wave interferometry was used to manifest interference patterns in a single run that were observable for over 150 ms free-expansion time. Finally, the CAL AI was used to remotely measure the Bragg laser photon recoil as a demonstration of the first quantum sensor using matter-wave interferometry in space. NASA’s Cold Atom Lab has operated on the International Space Station since 2018 to study quantum gases and mature quantum technologies in Earth’s orbit. Here, Williams et al., report on a series of pathfinding experiments exploring the first quantum sensor using atom interferometry in space.
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).