Recent proposals for testing foundations of physics assume Bose-Einstein condensates (BECs) as sources of atom interferometry sensors [1,2]. In this context, atom chip devices allow to build transportable BEC machines with high flux and high repetition rates [3], as demonstrated within the Quantus (drop tower) [4,5] and MAIUS (sounding rocket) [6] micro-gravity experiments, for instance. In such experiments, the proximity of the atoms to the chip surface is, however, limiting the optical access and the available interferometry time necessary for high-precision measurements.
This justifies the need of very well-designed BEC transport protocols in order to perform long-baseline, and thus precise, atom interferometry measurements.
In this talk, we present “shortcut-to-adiabaticity” (STA) [7] and “optimal control theory” (OCT) [8] protocols for the fast transport of BECs with atom chips, i.e. engineering transport ramps with durations not exceeding a 200 ms with realistic 3D anharmonic trapping. This controlled transport is implemented over large distances, typically of the order of 1-2 mm, i.e. of about 1,000 times the size of the atomic cloud. It will be shown that a subsequent optimized release and collimation step can generate ensembles of quantum gases with an optimal final expansion energy of just a few pK. The performance of this procedure will be explained by analyzing the collective excitations of the condensate. The robustness of the transport protocol against experimental imperfections is evaluated, and the respective advantages of STA vs. OCT protocols will be discussed. Such exquisite control features and robustness are crucial for the success of novel implementations of atom interferometry experiments in space, such as NASA’s Cold Atom Laboratory (CAL) [9] on the International Space Station (ISS) and for the NASA-DLR Bose-Einstein Condensate and Cold Atom Laboratory (BECCAL), which is presently in the planning phase [10].
[1] D. N. Aguilera et al, Class. Quantum Grav. 31, 115010 (2014).
[2] J. Hartwig et al, New J. Phys. 17, 035011 (2015).
[3] J. Rudolph et al, New J. Phys. 17, 065001 (2015).
[4] T. van Zoest et al, Science 328 ,1540 (2010).
[5] H. Müntinga et al, Phys. Rev. Lett. 110, 093602 (2013).
[6] D. Becker et al, submitted (2018).
[7] R. Corgier et al, New J. Phys. 20, 055002 (2018).
[8] S. Amri et al, in preparation (2018).
[9] CAL website https://coldatomlab.jpl.nasa.gov (accessed: 2018-05-30).
[10] NASA Fundamental Physics Science Standing Review Board, Future Opportunities for Fundamental Quantum Physics in Space. White paper (Apr. 2018).
