Measurement and feed-forward correction of the fast phase noise of lasers

TL;DR

This paper introduces a fiber-based system for measuring and correcting fast phase noise in lasers, significantly improving their stability for quantum applications like Rydberg gates.

Contribution

It presents a novel, fully-fiberized method for real-time detection and feed-forward correction of rapid laser phase fluctuations, enhancing quantum operation fidelity.

Findings

Achieved measurement noise floor below 0.1 Hz$^{2}$/Hz.

Suppressed laser phase noise by over 20 dB in the 1-10 MHz range.

Improved quantum gate performance using stabilized lasers.

Abstract

Lasers are the workhorse of quantum engineering in the atomic-molecular-optic community. However, phase noise of the laser, which can be especially large in popular semiconductor-based lasers, can limit fidelity of operation. Here, we present a fully-fiberized instrument detecting and correcting the fast, sub-microsecond, phase fluctuations of lasers. We demonstrate a measurement noise floor of less than 0.1 Hz$^{2}$/Hz, and a noise suppression of more than 20 dB for Fourier frequencies in the 1 to 10 MHz region (reaching up to 30 dB at 3 MHz), where noise is critical for Rydberg-based quantum gates. Finally, we observe the improvement offered by this fast phase noise eater on a Raman transition driven by two such stabilized lasers. These measurement and correction techniques are important tools for high-fidelity manipulation of the excited electronic states of atoms and molecules.