Fig. 2: Mach–Zehnder interferometry and the influence of vibrations on the ISS.

The main plot shows the relative population of rubidium atoms in the \(\left| {p}_{+}\right\rangle\) state after a Mach–Zehnder pulse sequence with T = 0.5 ms duration between Bragg pulses. Scanning the phase ϕ_laser of the traveling wave for the final laser pulse reveals a corresponding sinusoidal variation of N₊/N_tot. Eight independent data sets were analyzed, with up-to eight repetitions for each set. To increase the signal-to-noise ratio, the repeated images in each phase set were first summed, and the corresponding averaged images were fit to Thomas–Fermi profiles as described in “Methods”. The data plotted in light blue then yield the average N₊/N_tot for each ϕ_laser, with error bars given by the standard deviations. (Lower Inset) The first set of averaged absorption images after MZI, showing atoms oscillating between the \(\left| {p}_{+}\right\rangle\) and \(\left| {p}_{0}\right\rangle\) momentum states as ϕ_laser is increased. A small population occupying the \(\left| {p}_{-}\right\rangle\) state can also be seen. (Upper Inset) The influence of ISS vibrations is modeled (see “Methods”), with 2 ms granularity, to illustrate limitations to the atom-interferometer visibility for single-source ⁸⁷Rb BECs at larger T. Data for the acceleration a_z in the z-direction from the SAMS 121F04 accelerometer on the ISS was used for each day during which the MZI experiments were conducted, with dashed lines to guide the eye. Experimental results for T = 0.5 ms and 10 ms are included (orange triangles) for comparison.