Chip-scale superconducting quantum gravimeter combining a SQUID, a transmon, and a nanomechanical resonator

TL;DR

This paper proposes a chip-scale superconducting gravimeter that combines a SQUID, a transmon, and a nanomechanical resonator to achieve high sensitivity and bandwidth in gravitational measurements.

Contribution

It introduces a novel integrated architecture that enables compact, high-bandwidth gravimetry using superconducting quantum devices and nanomechanical resonators.

Findings

Projected sensitivity of 10^2–10^3 nGal/√Hz with sub-millisecond interrogation.

Electrical tunability and microwave calibration enhance practicality.

Design suppresses qubit dephasing, improving measurement accuracy.

Abstract

Precise gravitational measurements are vital for geophysics and inertial navigation, but compact gravimeters with high measurement bandwidth remain difficult to realize. We propose and analyze a chip-scale superconducting gravimeter in which a flux-tunable transmon qubit is coupled to a high quality factor ($Q_m$) nanomechanical beam. The beam is embedded in a SQUID loop placed in parallel with the qubit's flux-tunable SQUID; gravity induced beam displacement therefore modulates the qubit frequency through the SQUID flux and is mapped onto the qubit's geometric phase. A stroboscopic readout at mechanical revival times suppresses qubit mechanics dephasing, yielding a projected sensitivity of $10^2$--$10^3\,\mathrm{nGal}/\sqrt{\mathrm{Hz}}$ with sub-millisecond interrogation times. Electrical \emph{in situ} tunability and microwave-based calibration make this architecture a practical route toward compact, high-bandwidth on-chip gravimetry.