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.
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.
Quantum states of light allow for highly sensitive biosensing configurations, surpassing the limitations imposed by shot-noise. In this theoretical study, we focus on optical plasmonic sensors, which have extensive applications in disease diagnostics, including detection of diseases like HIV. Our investigation involves simulating the impact of quantum states of light, such as the NOON state and squeezed states, on enhancing the limit of detection in a plasmonic phase-sensing biosensor, surpassing coherent light states’ shot-noise limit. Specifically, we explore the use of quantum states to improve the limit of detection in phase-based biosensors for HIV detection, operating below the shot-noise limit. Through our analysis, we demonstrate that incorporating quantum states of light in surface plasmon resonance (SPR) biosensing leads to enhanced performance compared to classical states. Moreover, we take into account the impact of environmental losses in the biosensing setup, considering the real-world challenges in practical implementation. Our findings emphasize the potential of quantum SPR biosensors in the development of novel disease diagnostics devices.
We investigate the use of twin-mode quantum states of light with symmetric statistical features in their photon number for improving intensity-sensitive surface plasmon resonance (SPR) sensors. For this purpose, one of the modes is sent into a prism setup where the Kretschmann configuration is employed as a sensing platform and the analyte to be measured influences the SPR excitation conditions. This influence modifies the output state of light that is subsequently analyzed by an intensity-difference measurement scheme. We show that quantum noise reduction is achieved not only as a result of the sub-Poissonian statistical nature of a single mode, but also as a result of the nonclassical correlation of the photon number between the two modes. When combined with the high sensitivity of the SPR sensor, we show that the use of twin-mode quantum states of light notably enhances the estimation precision of the refractive index of an analyte. With this we are able to identify a clear strategy to further boost the performance of SPR sensors, which are already a mature technology in biochemical and medical sensing applications.
Surface plasmon resonance (SPR) sensors can reach the quantum noise limit of the optical readout field in various configurations. We demonstrate that two-mode intensity squeezed states produce a further enhancement in sensitivity compared with a classical optical readout when the quantum noise is used to transduce an SPR sensor signal in the Kretschmann configuration. The quantum noise reduction between the twin beams when incident at an angle away from the plasmonic resonance, combined with quantum noise resulting from quantum anticorrelations when on resonance, results in an effective SPR-mediated modulation that yields a measured sensitivity 5 dB better than that with a classical optical readout in this configuration. The theoretical potential of this technique points to resolving particle concentrations with more accuracy than is possible via classical approaches to optical transduction.
The utilization of quantum resources can enhance the sensitivity of conventional measurement techniques beyond the standard quantum limit (SQL). The objective of quantum metrology is to enable such quantum enhancements in practical devices. To achieve this objective, it is essential to have devices that are compatible with existing quantum resources operating within the SQL. Plasmonic sensors are promising candidates among these devices since they are extensively employed in biochemical sensing applications. Plasmonic sensors exhibit a response to slight variations in the local refractive index, which manifests as a shift in their resonance response. This shift, in turn, induces changes in the amplitude and phase of the probing light. By utilizing quantum states of light, such as NOON states, squeezed states, or Fock states, to probe these sensors, the measurement noise floor can be lowered, enabling the detection of signals below the SQL. In this study, we compare two configurations of quantum plasmonic sensing: phase-based and amplitude-based. By considering the Quantum Cramér Rao bound for both configurations, we demonstrate that the phase-based configuration can more effectively exploit the available quantum resources than the amplitude-based configuration. A limitation of this work is that it did not consider loss.
Abstract The signal-to-noise ratio is an important quantity in signal and image analysis that gives information about the quality of the signal and/or image of interest. When plasmonic biosensors are used to study how molecules interact in intermolecular binding reactions, the output signal and/or image must be of the highest quality to get the best value from our biosensors. Images of interest in this work are images of the binding region at the metal surface of the plasmonic biosensor. Improving the signal-to-noise ratio of these signals and/or images is a key area of research that can help scientists learn more about how different molecules interact with each other. Because these molecular entities can include a wide range of biomolecules, we can investigate different types of binding interactions. In this paper, we look at a theoretical two-mode image sensing framework that we use to model the signal-to-noise ratio in images generated by a plasmonic image-based biosensor. A Krestchmann configuration-based surface resonance sensor is used as a plasmonic biosensor. In the model, an example of how BSA and an antibody called IgG1 bind to the surface of a plasmonic biosensor are examined. Traditionally, classical states of light are used as probe states in the Krestchman configuration; in this paper, quantum states of light are considered alternative probe states. The effect of using quantum states of light, such as the Fock state, squeezed displaced states, and squeezed vacuum states, on the signal-to-noise ratio of images is investigated. This work also looks at the effect of losses in the sensing environment and changes in photon numbers in the input signal on the average signal-to-noise ratio of the output of the plasmonic biosensor. The novelty in the described work lies in the exploration of using a variety quantum states of light as probe states in a plasmonic image-based biosensor, specifically in the context of improving the signal-to-noise ratio of images captured from the binding region at the metal surface accounting for the impact of losses. It was found that some quantum states improve the signal-to-noise ratio of the plasmonic biosensor output image.
Quantum sensing is an emerging field of quantum optics that seeks to take advantage of quantum correlations available in quantum states of light to enable sensitivities beyond the fundamental classical limits. \nThe sensitivity of measurements and sensing apparatus when using classical states of light is limited to the shot-noise limit (SNL), which is achieved with coherent states of light. \n \nTwo-mode squeezed states of light (twin beams) have quantum correlations both in time and space, leading to temporal and spatial squeezing properties. \nSeveral applications can benefit from such noise reduction to enable new approaches, such as quantum-enhanced interferometry, quantum imaging, and quantum sensing. \nThe emergence of quantum technologies has been referred to as the second quantum revolution. \nFor metrology and sensing applications, in particular, it has led to new state-of-the-art sensitivity limits. \n \nIn this thesis, we discuss the implementation of quantum sensing based on squeezed states of light and plasmonic sensors as a platform for the demonstration of real-life quantum sensing. \nWe present a quantum-enhanced plasmonic sensing setup that can detect changes in the refractive index of air beyond the SNL. \nFurthermore, we generalize such experimental apparatus to probe an array of sensors using the quantum correlations present in different spatial locations to demonstrate a parallel quantum-enhanced plasmonic sensing scheme that can simultaneously detect changes in the refractive index of air in multiple locations with a single probing beam. \nThese results prove the applicability of twin beams for real-life applications based on plasmonic sensors. \nThe spatially resolved sensing scheme can be extended to pixel-size sensing of multiple sensors for multi-parameter estimation and detection applications to reach more complex sensing architectures.