Quantum sensors based on weak-value amplification cannot overcome decoherence

TL;DR

Weak-value amplification in quantum sensors cannot surpass decoherence effects, and even minimal decoherence negates its advantages, limiting its effectiveness in practical quantum sensing applications.

Contribution

This paper demonstrates that weak-value amplification cannot overcome decoherence, establishing a fundamental limitation in quantum sensing techniques.

Findings

Weak-value amplification offers no advantage over direct measurement under decoherence.

Decoherence severely impacts the performance of weak-value amplification.

Weak measurements are vulnerable to even small levels of decoherence.

Abstract

Sensors that harness exclusively quantum phenomena (such as entanglement) can achieve superior performance compared to those employing only classical principles. Recently, a technique based on postselected, weakly-performed measurements has emerged as a method of overcoming technical noise in the detection and estimation of small interaction parameters, particularly in optical systems. The question of which other types of noise may be combatted remains open. We here analyze whether the effect can overcome decoherence in a typical field sensing scenario. Benchmarking a weak, postselected measurement strategy against a strong, direct strategy we conclude that no advantage is achievable, and that even a small amount of decoherence proves catastrophic to the weak-value amplification technique.