A Tale of Two Interferometers

We present progress toward the realization of a long-baseline light-pulse atom interferometer for precision measurements of time-varying gravitational potentials. This instrument is designed to operate in regimes where environmental dynamics play an increasingly important role, motivating the development of advanced modeling and analysis tools alongside the hardware.

To support this effort, we are constructing a high-fidelity digital twin of the interferometer that integrates atomic trajectories, light–atom interactions, and control-system dynamics within a unified simulation framework. This model is used to reproduce experimental observables, guide system optimization, and assess performance in the presence of time-dependent disturbances. We report recent progress in training and validating the digital twin against measured data, and discuss its role in improving robustness and interpretability as the instrument scales to longer baselines.

Building on this modeling framework, we introduce a sensitivity function for atom interferometers probing time-varying gravitational potentials that exhibits a triangular temporal response. We further extend this sensitivity function to account for finite beam-splitter and mirror pulse durations, enabling consistent treatment of phase accumulation during realistic light–atom interactions. This formulation provides an intuitive and quantitative description of interferometer response to nonstationary and broadband gravitational signals, and interfaces naturally with the digital-twin model for validation and performance prediction.