Quantum plasmonic sensing: beyond the shot-noise and diffraction limit

TL;DR

This paper explores how quantum resources can enhance the sensitivity of plasmonic sensors beyond classical limits, even with system losses, by combining quantum light and electromagnetic confinement in a compact device.

Contribution

It demonstrates the potential of quantum-enhanced plasmonic interferometers to surpass shot-noise limits despite losses, advancing sensing technology.

Findings

Quantum resources improve sensitivity beyond shot-noise limit

Losses in plasmonic systems can be mitigated with quantum techniques

Enhanced resolution achieved in compact, sub-diffraction devices

Abstract

Photonic sensors have many applications in a range of physical settings, from measuring mechanical pressure in manufacturing to detecting protein concentration in biomedical samples. A variety of sensing approaches exist, and plasmonic systems in particular have received much attention due to their ability to confine light below the diffraction limit, greatly enhancing sensitivity. Recently, quantum techniques have been identified that can outperform classical sensing methods and achieve sensitivity below the so-called shot-noise limit. Despite this significant potential, the use of definite photon number states in lossy plasmonic systems for further improving sensing capabilities is not well studied. Here, we investigate the sensing performance of a plasmonic interferometer that simultaneously exploits the quantum nature of light and its electromagnetic field confinement. We show that, despite the presence of loss, specialised quantum resources can provide improved sensitivity and resolution beyond the shot-noise limit within a compact plasmonic device operating below the diffraction limit.