Fast and Automated Optical Polarization Compensation of Fiber Unitaries

TL;DR

This paper introduces a rapid, automated polarization compensation method for optical fibers using liquid crystals, achieving high fidelity and robustness essential for quantum communication and optical systems.

Contribution

The paper presents a novel fast and automated polarization compensation technique combining polarimetry and liquid crystal control, avoiding stochastic or cryptographic methods.

Findings

Achieves over 99% fidelity in polarization compensation

Requires fewer than six iterations on average

Can be fine-tuned to exceed 99.5% fidelity

Abstract

The polarization of light is critical in various applications, including quantum communication, where the photon polarization encoding a qubit can undergo uncontrolled changes when transmitted through optical fibers. Bends in the fiber, internal and external stresses, and environmental factors cause these polarization changes, which lead to errors and therein limit the range of quantum communication. To prevent this, we present a fast and automated method for polarization compensation using liquid crystals. This approach combines polarimetry based on a rotating quarter-waveplate with high-speed control of the liquid-crystal cell, offering high-fidelity compensation suitable for diverse applications. Our method directly solves for compensation parameters, avoiding reliance on stochastic approaches or cryptographic metrics. Experimental results demonstrate that our method achieves over 99% fidelity within an average of fewer than six iterations, with further fine-tuning to reach above 99.5% fidelity, providing a robust solution for maintaining precise polarization states in optical systems.