Understanding the gravitational and magnetic environment of a very long baseline atom interferometer

TL;DR

The paper discusses the challenges and environmental control strategies for the Hannover VLBAI, a long baseline atom interferometer designed for ultra-precise gravity measurements to test fundamental physics.

Contribution

It provides an analysis of magnetic and gravitational environment control in VLBAI, achieving sub-10 nm/s² measurement uncertainty for fundamental physics experiments.

Findings

Residual magnetic field gradients cause minimal bias acceleration.

Gravity gradient effects are evaluated to be within a few nanometers per second squared.

The model enables VLBAI to serve as a calibration reference with high accuracy.

Abstract

By utilizing the quadratic dependency of the interferometry phase on time, the Hannover Very Long Baseline Atom Interferometer facility (VLBAI) aims for sub nm/s$^2$ gravity measurement sensitivity. With its 10 m vertical baseline, VLBAI offers promising prospects in testing fundamental physics at the interface between quantum mechanics and general relativity. Here we discuss the challenges imposed on controlling VLBAI's magnetic and gravitational environment and report on their effect on the device's accuracy. Within the inner 8 m of the magnetic shield, residual magnetic field gradients expect to cause a bias acceleration of only 6$\times$10$^{-14}$ m/s$^2$ while we evaluate the bias shift due to the facility's non-linear gravity gradient to 2.6 nm/s$^2$. The model allows the VLBAI facility to be a reference to other mobile devices for calibration purposes with an uncertainty below the 10 nm/s$^2$ level.