Effects of Systematic Error on Quantum-Enhanced Atom Interferometry

TL;DR

This paper analyzes how systematic state preparation errors affect quantum-enhanced atom interferometry, comparing different state schemes and identifying conditions for robustness and optimal estimation strategies.

Contribution

It provides a comprehensive framework for understanding the impact of state preparation errors on various quantum states used in atom interferometry and suggests improved estimation methods.

Findings

OAT is more susceptible to errors than TAT in spin-squeezing regime.

OAT shows robustness to errors in non-Gaussian regime due to Fisher-covariance matrix properties.

Biased or multi-parameter estimators can outperform traditional unbiased estimators.

Abstract

We develop a framework for describing the effects of systematic state preparation error in quantum-enhanced atom interferometry on sensing performance. We do this in the context of both spin-squeezed and non-Gaussian states for the two-axis-twisting (TAT), one-axis-twisting (OAT), and twist-and-turn (TNT) state preparation schemes, and derive general conditions for robustness and susceptibility of quantum states to state preparation error. In the spin-squeezing regime, we find that OAT is more susceptible to state preparation error than TAT due to its parameter-dependent phase space rotation. In the non-Gaussian regime, we find that OAT is robust to state preparation errors, which can be explained by a small ratio of off-diagonal to diagonal elements in its Fisher-covariance matrix. In contrast, TNT does not exhibit this robustness. We find that the single parameter unbiased estimators that are habitually used in quantum-enhanced atom interferometry are not always optimal, and that there may be occasions where biased estimators, or two-parameter unbiased estimators, lead to lower net error.