# Practical Advantages of Almost-Balanced-Weak-Values Metrological Techniques

## TL;DR

This paper compares Almost-Balanced Weak Values (ABWV) and Weak-Value Amplification (WVA) techniques for ultra-precise velocity measurements, demonstrating ABWV's practical advantages in sensitivity and robustness over long durations.

## Contribution

The study introduces and experimentally validates the advantages of ABWV over WVA in precision interferometric velocity measurements.

## Key findings

- ABWV achieves higher signal-to-noise ratios than WVA.
- ABWV allows longer integration times due to robustness against slow drifts.
- Velocity sensitivity of 60 fm/s achieved after 40 hours of measurement.

## Abstract

Precision measurements of ultra-small linear velocities of one of the mirrors in a Michelson interferometer are performed using two different weak-values techniques. We show that the technique of Almost-Balanced Weak Values (ABWV) offers practical advantages over the technique of Weak-Value Amplification (WVA), resulting in larger signal-to-noise ratios and the possibility of longer integration times due to robustness to slow drifts. As an example of the performance of the ABWV protocol we report a velocity sensitivity of 60 fm/s after 40 hours of integration time. The sensitivity of the Doppler shift due to the moving mirror is of 150 nHz.