Observation of Bose–Einstein condensates in an Earth-orbiting research lab


Quantum mechanics governs the microscopic world, where low mass and momentum reveal a natural wave–particle duality. Magnifying quantum behaviour to macroscopic scales is a major strength of the technique of cooling and trapping atomic gases, in which low momentum is engineered through extremely low temperatures. Advances in this field have achieved such precise control over atomic systems that gravity, often negligible when considering individual atoms, has emerged as a substantial obstacle. In particular, although weaker trapping fields would allow access to lower temperatures1,2, gravity empties atom traps that are too weak. Additionally, inertial sensors based on cold atoms could reach better sensitivities if the free-fall time of the atoms after release from the trap could be made longer3. Planetary orbit, specifically the condition of perpetual free-fall, offers to lift cold-atom studies beyond such terrestrial limitations. Here we report production of rubidium Bose–Einstein condensates (BECs) in an Earth-orbiting research laboratory, the Cold Atom Lab. We observe subnanokelvin BECs in weak trapping potentials with free-expansion times extending beyond one second, providing an initial demonstration of the advantages offered by a microgravity environment for cold-atom experiments and verifying the successful operation of this facility. With routine BEC production, continuing operations will support long-term investigations of trap topologies unique to microgravity4,5, atom-laser sources6, few-body physics7,8 and pathfinding techniques for atom-wave interferometry9,10,11,12.

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Fig. 1: CAL hardware configuration.
Fig. 2: BEC production in CAL on the Earth and in orbit.
Fig. 3: Onset of Bose–Einstein condensation in low Earth orbit.
Fig. 4: In-orbit free expansion of ultracold atoms.

Data availability

Source data for Fig. 4 are provided with the paper. The datasets generated and analysed during the current study are available from the corresponding authors on reasonable request.


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We gratefully acknowledge the contributions of current and former members of CAL’s management and technical teams, T. Winn, K. Muse, L. Clonts, J. Lam, J. Liu, C. Tran, J. Tarsala, T. Tran, S. Haque, M. McKee, J. Trager, J. Mota, G. Miles, D. Strekalov, I. Li, S. Javidnia, A. Sengupta, D. Conroy, A. Croonquist, E. Burt, M. Krutzik, S. Kulas and V. Schkolnik, and the ColdQuanta team, including E. Salim, L. Czaia, J. Ramirez-Serrano, J. Duggan, and D. Anderson. We recognize the continuing support of JPL’s Astronomy, Physics and Space Technology Directorate, L. Livesay, T. Gaier, D. Coulter, C. Lawrence and U. Israelsson. We thank CAL’s principal investigators and science team members, N. Bigelow, N. Lundblad, C. Sackett, E. Cornell, P. Engels and M. Mossman, for their guidance, along with CAL’s Science Review Board, including B. DeMarco and R. Walsworth. We also recognize the steadfast support from NASA’s Division of Space, Life, and Physical Sciences Research and Applications (SLPSRA), C. Kundrot, D. Malarik, M. Lee, B. Carpenter and D. Griffin. This work was funded by NASA’s SLPSRA programme office, and operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. US Government sponsorship is acknowledged.

Author information




D.C.A., J.R.W. and E.R.E. optimized and operated the instrument during the CAL commissioning phase, collected and analysed the associated data, and prepared this manuscript. D.C.A., J.R.W. and E.R.E. were responsible for instrument hardware integration, experimental operation, optimization and data acquisition during the CAL integration and test phase. D.C.A. led CAL’s ground testbed and the integration and testing of the science module hardware. J.R.W. led flight instrument operation and atom-interferometer-related tests. E.R.E. led integration and operation of CAL’s engineering model testbed. C.D. established and led the mission operations and ground data systems during commissioning. J.R.K. prepared and coordinated ISS installation procedures and operations. J.R.K. and J.M.K. led the laser and optics subsystems and operated the system post-commissioning. R.F.S., K.O., N.Y. and N.E.L. led technical planning and provided guidance across multiple subsystems during the integration and test phase. R.J.T. proposed the instrument, gave scientific guidance and coordinated with principal investigators as CAL project scientist. All authors read, edited and approved the final manuscript.

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Correspondence to David C. Aveline or Robert J. Thompson.

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Peer review information Nature thanks A. Roura and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Extended data figures and tables

Extended Data Fig. 1 Science module optical beams.

a, An illustrative cross-section of the science module in the yz plane, showing the optical beam paths for laser cooling and imaging. Collimators (depicted in blue) each accept optical fibre inputs and direct free-space beams into the vacuum chamber. In the source cell, elliptical beam collimators create a two-dimensional (2D) MOT (the x-axis collimator is not shown). A cold atomic beam is directed (its flux enhanced by the 2D MOT push beam) up to the UHV science cell, where >109 atoms are collected in a three-dimensional MOT. In this region, laser cooling beams labelled ‘MOT (a)’ and ‘MOT (b)’ are directed along the yz plane, while a third collimator (not shown) sends its 11-mm-diameter beam (dotted circle) along the x-axis to complete the MOT. Each beam is retro-reflected by a mirror to create a full six-beam MOT located about 15 mm below the atom chip, which forms the topmost wall of the UHV chamber. CAL’s primary imaging beam (also 11 mm in diameter) is directed parallel to the chip surface along the y axis just under the chip, labelled as ‘Imaging (y)’. Fluorescence and absorption images along this axis are collected on the ‘CMOS (y)’ camera. Alternatively, through-chip imaging along the z axis can be collected by the ‘CMOS (z)’ camera, with an absorption imaging beam provided by the ‘Imaging (z)’ light that passes through a 0.75-mm-diameter aperture of the source cell. This aperture provides differential pumping to maintain UHV conditions in the science cell while the source cell runs at higher pressures of Rb and K. The background pressure of Rb and K is controlled by running independent current through each of two alkali metal dispensers: one containing Rb, and the other K. Atoms are collected in the MOT before undergoing molasses cooling and becoming confined by the coil-generated magnetic trap. The trapped cloud is then transported up 15 mm by a second pair of coils, and then loaded into the atom chip trap. b, A photograph of a science module without its front clam-shell of magnetic shields, showing the mechanical structure that rigidly supports the vacuum and optical hardware, as well as some of the thermal management components. More details of the science module and control hardware can be found in ref. 40.

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Aveline, D.C., Williams, J.R., Elliott, E.R. et al. Observation of Bose–Einstein condensates in an Earth-orbiting research lab. Nature 582, 193–197 (2020). https://doi.org/10.1038/s41586-020-2346-1

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