Conditional Quantum Plasmonic Sensing

TL;DR

This paper introduces a conditional detection protocol for quantum plasmonic sensing that enhances signal-to-noise ratio by controlling quantum fluctuations, enabling sensitive detection of delicate samples with weak plasmonic signals.

Contribution

The paper presents a novel quantum sensing protocol based on plasmon subtraction that improves sensitivity by managing quantum fluctuations in plasmonic fields.

Findings

Conditional detection improves signal-to-noise ratio.

Plasmon subtraction controls quantum fluctuations.

Enhanced sensing of delicate samples with weak signals.

Abstract

The possibility of using weak optical signals to perform sensing of delicate samples constitutes one of the main goals of quantum photonic sensing. Furthermore, the nanoscale confinement of electromagnetic near fields in photonic platforms through surface plasmon polaritons has motivated the development of highly sensitive quantum plasmonic sensors. Despite the enormous potential of plasmonic platforms for sensing, this class of sensors is ultimately limited by the quantum statistical fluctuations of surface plasmons. Indeed, the fluctuations of the electromagnetic field severely limit the performance of quantum plasmonic sensing platforms in which delicate samples are characterized using weak near-field signals. Furthermore, the inherent losses associated with plasmonic fields levy additional constraints that challenge the realization of sensitivities beyond the shot-noise limit. Here, we introduce a protocol for quantum plasmonic sensing based on the conditional detection of plasmons. We demonstrate that the conditional detection of plasmonic fields, via plasmon subtraction, provides a new degree of freedom to control quantum fluctuations of plasmonic fields. This mechanism enables improvement of the signal-to-noise ratio of photonic sensors relying on plasmonic signals that are comparable to their associated field fluctuations. Consequently, the possibility of using weak plasmonic signals to sense delicate samples, while preserving the sample properties, has important implications for molecule sensing, and chemical detection .