Chip scale superconducting quantum gravimeter based on a SQUID transmon mechanical resonator

Abstract: Precise gravitational measurements are vital for geophysics and inertial navigation, but current platforms struggle to combine absolute accuracy with high-bandwidth tracking. We address this challenge with a chip-scale superconducting gravimeter that couples a flux-tunable transmon qubit to a high-$Q$ mechanical resonator. We embed the mechanical element inside the qubit's SQUID loop. This allows us to exploit the Josephson potential's nonlinearity, creating a motion-dependent inductance that maps gravitational displacement onto the qubit's geometric phase. Using a stroboscopic measurement protocol, we suppress mechanical decoherence at revival times. This yields a predicted sensitivity of $10^2\,\mathrm{nGal}/\sqrt{\mathrm{Hz}}$, approaching the performance of atomic sensors but with kilohertz-rate sampling. With electrical {in situ} tunability and SI traceability via microwave spectroscopy, this architecture offers a practical route to high-speed, quantum-limited on-chip gravimetry.