Bias in error-corrected quantum sensing

TL;DR

This paper investigates how quantum error correction biases the output of quantum sensors, affecting their sensitivity and accuracy, and discusses methods to correct this bias in continuous-time QEC settings.

Contribution

It provides a detailed analysis of bias introduced by QEC in quantum sensing and proposes strategies to mitigate this bias for improved sensor performance.

Findings

Bias can significantly reduce sensor sensitivity if uncorrected.

Proper correction methods can eliminate bias and restore accurate sensing.

Incorrect analysis without bias correction leads to misleading conclusions.

Abstract

The sensitivity afforded by quantum sensors is limited by decoherence. Quantum error correction (QEC) can enhance sensitivity by suppressing decoherence, but it has a side-effect: it biases a sensor's output in realistic settings. If unaccounted for, this bias can systematically reduce a sensor's performance in experiment, and also give misleading values for the minimum detectable signal in theory. We analyze this effect in the experimentally-motivated setting of continuous-time QEC, showing both how one can remedy it, and how incorrect results can arise when one does not.