Weak measurement of photon polarization by back-action induced path interference

TL;DR

This paper demonstrates a robust optical weak measurement technique for photon polarization using path interference, achieving high weak values with minimal back-action and high resistance to experimental imperfections.

Contribution

It introduces a novel method for weak measurement of photon polarization via path interference, controlling measurement strength without additional decoherence.

Findings

High weak values achieved at low visibilities

Method is robust against experimental imperfections

Back-action is effectively generated without decoherence

Abstract

The essential feature of weak measurements on quantum systems is the reduction of measurement back-action to negligible levels. To observe the non-classical features of weak measurements, it is therefore more important to avoid additional back-action errors than it is to avoid errors in the actual measurement outcome. In this paper, it is shown how an optical weak measurement of diagonal (PM) polarization can be realized by path interference between the horizontal (H) and vertical (V) polarization components of the input beam. The measurement strength can then be controlled by rotating the H and V polarizations towards each other. This well-controlled operation effectively generates the back-action without additional decoherence, while the visibility of the interference between the two beams only limits the measurement resolution. As the experimental results confirm, we can obtain extremely high weak values, even at rather low visibilities. Our method therefore provides a realization of weak measurements that is extremely robust against experimental imperfections.