Quantum metrology with nonclassical states of atomic ensembles

TLDR

Quantum technologies use entanglement to advance computing, measurement, and communication, and recent progress—especially with atoms—has enabled the creation of many‑particle entangled states that couple strongly to forces and light, making them ideal for ultra‑precise sensing and timekeeping. The article aims to generate non‑classical atomic states for phase estimation in clocks and interferometers, leveraging many‑body entanglement to boost measurement sensitivity. It reviews theory and experiments with atomic ensembles that demonstrate many‑particle entanglement and quantum‑enhanced metrology.

Abstract

Quantum technologies exploit entanglement to revolutionize computing, measurements, and communications. This has stimulated the research in different areas of physics to engineer and manipulate fragile many-particle entangled states. Progress has been particularly rapid for atoms. Thanks to the large and tunable nonlinearities and the well developed techniques for trapping, controlling and counting, many groundbreaking experiments have demonstrated the generation of entangled states of trapped ions, cold and ultracold gases of neutral atoms. Moreover, atoms can couple strongly to external forces and light fields, which makes them ideal for ultra-precise sensing and time keeping. All these factors call for generating non-classical atomic states designed for phase estimation in atomic clocks and atom interferometers, exploiting many-body entanglement to increase the sensitivity of precision measurements. The goal of this article is to review and illustrate the theory and the experiments with atomic ensembles that have demonstrated many-particle entanglement and quantum-enhanced metrology.