Characterization of an integrated multipath interferometer on a CubeSat in space

We demonstrate a compact, stable, and reconfigurable photonic platform suitable for space-based experiments, implemented as a three-path interferometer on a chip. The device enables precise control of optical paths using ultrafast laser writing and has thermo-optic phase shifters for multi-path interference. Our laboratory characterization includes temperature-dependent calibration of the optical switches, ensuring predictable and stable operation. In orbit on a 3U CubeSat, the interferometer maintains stable phase and switching performance, validating the robustness of integrated waveguides and two-dimensional emitters under space conditions. Using this platform, we perform a Sorkin-type experiment to probe higher-order interference, demonstrating that the system provides the phase stability and controllability required for fundamental tests of quantum mechanics as well as future applications in quantum key distribution and on-chip photonic processing in space.