Ultrasensitive Beam Deflection Measurement via Interferometric Weak Value Amplification

TL;DR

This paper demonstrates an interferometric weak value amplification technique that significantly enhances the sensitivity of beam deflection measurements, achieving femtometer and femtoradian resolution.

Contribution

It introduces a novel interferometric weak value method for amplifying tiny beam deflections, enabling unprecedented measurement precision.

Findings

Measured angular deflections down to 560 femtoradians

Achieved linear travel measurement of 20 femtometers

Experimental results agree with theoretical predictions

Abstract

We report on the use of an interferometric weak value technique to amplify very small transverse deflections of an optical beam. By entangling the beam's transverse degrees of freedom with the which-path states of a Sagnac interferometer, it is possible to realize an optical amplifier for polarization independent deflections. The theory for the interferometric weak value amplification method is presented along with the experimental results, which are in good agreement. Of particular interest, we measured the angular deflection of a mirror down to 560 femtoradians and the linear travel of a piezo actuator down to 20 femtometers.