Enhanced phase-based plasmonic biosensing with quantum states of light

Abstract Our research aims to create a theoretical framework that may be used to improve phase-based surface plasmon resonance (SPR) biosensor precision beyond the shot noise limit by utilizing quantum states including squeezed states and NOON states. For this work, a two-mode phase sensing setup model is created. One of the two arms of the two mode model of this model has an integrated SPR system based on the Krestchmann arrangement. An experiment involving phase-based plasmonic biosensing is modeled using the two-mode setup. The state preparation, the biosensing component, and the measurement comprise the three main components of the model. The measurement varies depending on the particular input state. Quantum noise reduction for quantum states results from the combination of the sub-Poissonian statistical structure of a single mode and the non-classical correlation of the photon number between the two modes (entanglement). We show that when combined with the high sensitivity of the SPR sensor, the use of two-mode quantum states of light considerably increases the estimation precision of the refractive index of an analyte. Here, we use distilled water diluted BSA solutions at different concentrations that correlate to different refractive indices to reproduce a static phase-based SPR biosensor. Both lossless and lossy circumstances were taken into consideration for the model. The NOON state and the product coherent squeezed vacuum (PCSV) state are the two main quantum states taken into consideration in this work. The PCSV state exhibited the better limit of detection (LOD) among the states that we measured, suggesting that it is a promising candidate for the development of quantum biosensing systems. The effect of losses will require more investigation, but this work enables us to identify a precise course of action for enhancing the performance of the phase-based surface plasmon resonance sensor even further. Phase-based quantum SPR sensors have yet to be thoroughly examined, but intensity-based quantum SPR sensors have previously been extensively researched in the biochemical and medical sensing domains.