Abstract Quantum‐enhanced sensing and metrology pave the way for promising routes to fulfil the present day fundamental and technological demands for integrated chips which surpass the classical functional and measurement limits. The most precise measurements of optical properties such as phase or intensity require quantum optical measurement schemes. These non‐classical measurements exploit phenomena such as entanglement and squeezing of optical probe states. They are also subject to lower detection limits as compared to classical photodetection schemes. Biosensing with non‐classical light sources of entangled photons or squeezed light holds the key for realizing quantum optical bioscience laboratories which could be integrated on chip. Single‐molecule sensing with such non‐classical sources of light would be a forerunner to attaining the smallest uncertainty and the highest information per photon number. This demands an integrated non‐classical sensing approach which would combine the subtle non‐deterministic measurement techniques of quantum optics with the device‐level integration capabilities attained through nanophotonics as well as nanoplasmonics. In this back drop, we review the underlining principles in quantum sensing, the quantum optical probes and protocols as well as state‐of‐the‐art building blocks in quantum optical sensing. We further explore the recent developments in quantum photonic/plasmonic sensing and imaging together with the potential of combining them with burgeoning field of coupled cavity integrated optoplasmonic biosensing platforms.
Abstract Quantum‐enhanced sensing and metrology pave the way for promising routes to fulfil the present day fundamental and technological demands for integrated chips which surpass the classical functional and measurement limits. The most precise measurements of optical properties such as phase or intensity require quantum optical measurement schemes. These non‐classical measurements exploit phenomena such as entanglement and squeezing of optical probe states. They are also subject to lower detection limits as compared to classical photodetection schemes. Biosensing with non‐classical light sources of entangled photons or squeezed light holds the key for realizing quantum optical bioscience laboratories which could be integrated on chip. Single‐molecule sensing with such non‐classical sources of light would be a forerunner to attaining the smallest uncertainty and the highest information per photon number. This demands an integrated non‐classical sensing approach which would combine the subtle non‐deterministic measurement techniques of quantum optics with the device‐level integration capabilities attained through nanophotonics as well as nanoplasmonics. In this back drop, we review the underlining principles in quantum sensing, the quantum optical probes and protocols as well as state‐of‐the‐art building blocks in quantum optical sensing. We further explore the recent developments in quantum photonic/plasmonic sensing and imaging together with the potential of combining them with burgeoning field of coupled cavity integrated optoplasmonic biosensing platforms.
Modern quantum technology currently experiences extensive advances in applicability in communications, cryptography, computing, metrology and lithography. Harnessing this technology platform for chem/bio sensing scenarios is an appealing opportunity enabling ultra-sensitive detection schemes. This is further facilliated by the progress in fabrication, miniaturization and integration of visible and infrared quantum photonics. Especially, the combination of efficient single-photon sources together with waveguiding/sensing structures, serving as active optical transducer, as well as advanced detector materials is promising integrated quantum photonic chem/bio sensors. Besides the intrinsic molecular selectivity and non-destructive character of visible and infrared light based sensing schemes, chem/bio sensors taking advantage of non-classical light sources promise sensitivities beyond the standard quantum limit. In the present review, recent achievements towards on-chip chem/bio quantum photonic sensing platforms based on N00N states are discussed along with appropriate recognition chemistries, facilitating the detection of relevant (bio)analytes at ultra-trace concentration levels. After evaluating recent developments in this field, a perspective for a potentially promising sensor testbed is discussed for reaching integrated quantum sensing with two fiber-coupled GaAs chips together with semiconductor quantum dots serving as single-photon sources.
In the field of optics and photonics, plasmonic sensors have garnered considerable interest due to their outstanding sensitivity and impressive capacity to control light at the nanoscale. These sensors enable the integration of biochemical sensing platforms by exploiting the combination of enhanced and localized electromagnetic fields at the metal–dielectric interface, and they operate effectively below the diffraction limit. The performance of conventional plasmonic sensors, despite their practical development and commercial success, remains inherently constrained by classical noise constraints, owing to the quantum fluctuations of light, known as the shot-noise limit. Recent advances have introduced quantum optical resources such as entangled and squeezed light states to overcome inherent classical restrictions, thus giving rise to the quantum plasmonic sensing field. This interdisciplinary field combines the ability to enhance electric field capabilities with the precision of quantum metrology, enabling ultrasensitive chemical and biological detection that surpasses classical precision thresholds. In the last decades, theoretical models and experimental demonstrations have greatly advanced the development of quantum plasmonic sensors, improving our comprehension of quantum light–matter interactions and facilitating novel nanoscale sensing designs. This chapter provides a comprehensive overview of the fundamental principles, latest developments, and major concepts that have driven progress in quantum plasmonic sensing and shows that quantum components are being integrated into plasmonic systems, thereby transforming optical sensing to the quantum level.
Optical chips for quantum photonics are cutting-edge technology, merging photonics and quantum mechanics to manipulate light at the quantum level. These chips are crucial for advancing quantum computing, secure communication, and precision sensing by integrating photonic components such as waveguides, beam splitters, and detectors to manipulate single photons, the fundamental carriers of quantum information. Key advancements in optical chips include low-loss waveguides, efficient single-photon sources, and high-fidelity quantum gates, all essential for scalable quantum circuits. Integrating these circuits on a chip offers significant advantages in miniaturization, stability, and reproducibility over traditional bulk optics setups. Recent breakthroughs in materials science and nanofabrication have propelled the field forward, enabling the production of chips with higher precision and lower defect rates. Silicon photonics, in particular, has become a prominent platform due to its compatibility with existing semiconductor manufacturing processes, facilitating the integration of quantum photonic circuits with classical electronic systems. Here, we share our vision of the future of optical chips for quantum photonics, which hold promise for various applications. In quantum computing, they enable the development of compact and scalable quantum processors. In communication, they provide the foundation for ultra-secure quantum networks through quantum key distribution. In sensing, they allow for high-precision measurements that surpass classical limits. As research progresses, optical chips are expected to play a critical role in realizing the full potential of quantum technologies.
Abstract Quantum sensing (QS) is a rapidly developing field at the intersection of physics, biology, and nanotechnology. It holds great promise for improving how we detect biomolecules in health, diagnostics, and environmental monitoring, and this potential is reflected in the rapid development and growing interest in advanced biosensing technologies. Traditional sensing methods, while useful, often face limits in sensitivity, speed, and the ability to analyze tiny amounts or subtle changes in biomolecules. QS uses coherence, entanglement, and superposition to achieve much higher sensitivity and precision than classical techniques. These technologies rely on advanced platforms like nitrogen-vacancy centers in diamonds, quantum dots. They can measure tiny changes in magnetic fields, electric charges, or fluorescence signals caused by biomolecules like proteins, DNA, lipids, carbohydrates and metabolites. This review explains the fundamental principles behind QS and explores how various physical platforms are used to detect and study biomolecules. It highlights recent breakthroughs in detecting single molecules, monitoring enzymatic reactions in real time, and imaging biological structures with quantum-level detail. We also discuss how nanotechnology is powering the field, improving integration through nanoparticle coupling, microfluidics, and specialized bio interfaces to target and amplify signals in practical settings. This review discusses current efforts to overcome existing challenges and highlights future directions, including the development of quantum-enhanced clinical sensors, integration with artificial intelligence for data analysis, and hybrid quantum–classical sensing strategies. These advances are expected to accelerate the translation of quantum biosensing technologies from laboratory demonstrations to practical clinical and environmental applications in the coming decade.
Abstract The development of quantum‐enabled photonic technologies has opened new avenues for advanced illumination across diverse fields, including sensing, computing, materials, and integration. This review highlights how Quantum‐enhanced sensing and imaging exploit nonclassical correlations to attain unprecedented accuracy in chaotic environments. As well as guaranteeing secure communications, quantum cryptography, protected by physical principles, ensures unbreakable cryptographic key exchange. As quantum computing speed increases exponentially, previously unimplementable uses for classical computers become feasible. On‐chip integration enables the mass production of quantum photonic components for pervasive applications by facilitating miniaturization and scalability. A powerful and flexible platform is produced when classical and quantum systems are combined. Quantum spin liquids and other topological materials can maintain their quantum states while subject to decoherence. Despite challenges with decoherence, production, and commercialization, quantum photonics is an exciting new area of study that promises lighting techniques impossible with conventional optics. To realize this promise, researchers from several fields must work together to solve complex technical problems and decode fundamental physics. Finally, advances in quantum‐enabled photonics have the potential to evolve quantum photonic devices and cutting‐edge imaging methods and usher in a new age of lighting options based on quantum dots.
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.