Quantum-enhanced interferometry and the structure of twisted states

TL;DR

This paper explores the limits of quantum-enhanced interferometry using one-axis twisting, revealing how fine structures in entangled states determine the achievable precision in realistic experiments.

Contribution

It provides a detailed analysis of the structure of twisted states and identifies minimal experimental requirements for optimal quantum interferometry.

Findings

Fine structures in quantum states are crucial for quantum advantage.

The scale of state structures determines the minimal precision needed.

Results can guide development of ultra-precise interferometers.

Abstract

Preparation of a non-classically correlated state is the first step of any quantum-enhanced interferometric protocol. An efficient method is the one-axis twisting, which entangles a collection of initially uncorrelated particles by means of two-body interactions. Here we investigate the limits of the quantum improvement which can be reached with this method in realistic experimental conditions. We demonstrate that the usefulness of this entangling mechanism is a result of fine structures introduced into the quantum state. The scale at which these structures vary allows us to identify the minimal requirements for the precision of the complete interferometric sequence. Our results---especially the explanation of the underlying principle of the entangling method---may help to develop ultra-precise interferometers.