Fig. 1: Atom interferometer set up onboard the ISS.
a Cut of the upper region of the physics package of SM-3 to expose the interior components and the path of the retro-reflected Bragg beam (red) inside the vacuum system. The expanded region shows the beam entering the vacuum chamber through a window and between pairs of Z- and U-traces (blue) and H-traces (yellow) on the atom chip. Dimensions of the upper vacuum cell are given to illustrate the compactness of the science region accommodating our AI experiments. Note that the entire CAL payload occupies only 0.4 m3 on the ISS with a mass of approximately 230 kg. b Space-time diagram of an ideal Mach–Zehnder interferometer, where three retro-reflected laser pulses (red) are applied in a sequence of \(\frac{\pi }{2}\)-π-\(\frac{\pi }{2}\) pulses, with pulse separation times T, to create a superposition and then recombination of the initial atom cloud into two motional states (\(\left| {p}_{+}\right\rangle\) and \(\left| {p}_{0}\right\rangle\) given by blue and yellow clouds respectively). c Ramsey atom interferometer diagram using a sequence of \(\frac{\pi }{2}\)-\(\frac{\pi }{2}\) pulses to explore shear-wave atom interferometry at long time-of-flight tTOF. For sufficiently short T, used for photon recoil measurements, the outputs are similar to that of the MZI.
