Quantum metrology with nonclassical states of atomic ensembles

TL;DR

This paper reviews how nonclassical states of atomic ensembles, harnessing many-particle entanglement, enhance the sensitivity of quantum measurements like atomic clocks and interferometers.

Contribution

It provides a comprehensive overview of the theory and experimental progress in generating and utilizing entangled atomic states for quantum metrology.

Findings

Demonstrated generation of entangled states in atomic ensembles

Enhanced measurement sensitivity using many-body entanglement

Reviewed experimental techniques for quantum-enhanced sensing

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.