Quantum sensors based on weak-value amplification cannot overcome decoherence

TLDR

Quantum sensors exploiting entanglement can outperform classical ones, and weak‑value amplification has been proposed to mitigate technical noise in optical measurements, but it is unclear whether it can counter other noise sources such as decoherence. The study investigates whether weak‑value amplification can overcome decoherence in a typical field‑sensing scenario. The authors benchmark a weak, postselected measurement strategy against a strong, direct strategy in a field‑sensing setup. They find that no advantage is achieved and even minimal decoherence renders weak‑value amplification ineffective.

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.