Photonic polarization gears for ultra-sensitive angular measurements

TL;DR

This paper introduces a photonic gear system that amplifies angular measurement sensitivity by converting mechanical rotations into polarized light rotations, achieving super-resolution and robustness to photon loss, with potential for significant improvements in optical angular sensing.

Contribution

The authors demonstrate a novel photonic gear that combines quantum states and classical amplification to enhance angular measurement precision beyond current limits.

Findings

Achieved NOON-like states with up to 100 quanta of angular momentum.

Enhanced angular measurement sensitivity by nearly two orders of magnitude.

Robustness to photon loss while maintaining high precision.

Abstract

Quantum metrology bears a great promise in enhancing measurement precision, but is unlikely to become practical in the near future. Its concepts can nevertheless inspire classical or hybrid methods of immediate value. Here, we demonstrate NOON-like photonic states of m quanta of angular momentum up to m=100, in a setup that acts as a "photonic gear", converting, for each photon, a mechanical rotation of an angle {\theta} into an amplified rotation of the optical polarization by m{\theta}, corresponding to a "super-resolving" Malus' law. We show that this effect leads to single-photon angular measurements with the same precision of polarization-only quantum strategies with m photons, but robust to photon losses. Moreover, we combine the gear effect with the quantum enhancement due to entanglement, thus exploiting the advantages of both approaches. The high "gear ratio" m boosts the current state-of-the-art of optical non-contact angular measurements by almost two orders of magnitude.