Dual matter-wave inertial sensors in weightlessness

Quantum technology based on cold-atom interferometers is showing great promise for fields such as inertial sensing and fundamental physics. However, the finite free-fall time of the atoms limits the precision achievable on Earth, while in space interrogation times of many seconds will lead to unprecedented sensitivity. Here we realize simultaneous ⁸⁷Rb-³⁹K interferometers capable of operating in the weightless environment produced during parabolic flight. Large vibration levels (10^-2 g Hz^-1/2), variations in acceleration (0-1.8 g) and rotation rates (5° s^-1) onboard the aircraft present significant challenges. We demonstrate the capability of our correlated quantum system by measuring the Eötvös parameter with systematic-limited uncertainties of 1.1 × 10^-3 and 3.0 × 10^-4 during standard- and microgravity, respectively. This constitutes a fundamental test of the equivalence principle using quantum sensors in a free-falling vehicle. Our results are applicable to inertial navigation, and can be extended to the trajectory of a satellite for future space missions.