Quantum sensing to suppress systematic errors with measurements in the Zeno regime

TL;DR

This paper introduces a simple quantum sensing protocol in the Zeno regime that reduces systematic errors in magnetic field measurements, enabling improved estimation accuracy despite fluctuating coherence times.

Contribution

The authors propose a novel measurement protocol in the Zeno regime that suppresses systematic errors without needing precise coherence time characterization.

Findings

Estimation uncertainty scales as L^{1/4} with the number of measurements.

The protocol effectively reduces systematic errors in quantum magnetic sensing.

It operates successfully even with fluctuating coherence times.

Abstract

Quantum magnetic field sensing is an important technology for material science and biology. Although experimental imperfections affect the sensitivity, repetitions of the measurements decrease the estimation uncertainty by a square root of the total number of the measurements if there are only statistical errors. However, it is difficult to precisely characterize the coherence time of the system because it fluctuates in time in realistic conditions, which induces systematic errors. In this case, due to residual bias of the measured values, estimation uncertainty cannot be lowered than a finite value even in the limit of the infinite number of measurements. On the basis of the fact that the decoherence dynamics in the so-called Zeno regime are not significant compared to other regimes, we propose a novel but very simple protocol to use measurements in the Zeno regime for reducing systematic errors. Our scheme allows the estimation uncertainty $\delta ^2 \omega$ to scale as $L^{1/4}$ where $L$ denotes the number of the measurements even when we cannot precisely characterize the coherence time.