ABSTRACT Weak measurement has emerged as a pivotal technique in precision metrology, utilizing unique amplification effects to enhance the capabilities of quantum sensing and quantum imaging. Quantum sensing can provide systems with unprecedented accuracy and sensitivity by utilizing its quantum properties. Quantum imaging uses entangled photon states to capture information, enabling signal‐to‐noise ratio and resolution that surpass the limits of classical imaging. The synergistic integration of weak measurement with quantum sensing and imaging paves the way for next‐generation technologies with practical value, significantly advancing frontiers of precision metrology and imaging science. This review elucidates the fundamental theory of weak value amplification and comprehensively discusses the performance of weak measurement strategies in quantum sensing and imaging frameworks, highlighting both classical techniques and emerging quantum applications. It covers four main directions: nanostructure, 2D atomic crystal, biochemistry, and optical imaging, including from structural parameters characterization to chemical reaction sensing to nonlocal weak measurement microscopy. This work aims to discuss recent advances in weak measurement applications for quantum sensing and imaging platforms, while outlining future development opportunities arising from the convergence of these three fields.
ABSTRACT Weak measurement has emerged as a pivotal technique in precision metrology, utilizing unique amplification effects to enhance the capabilities of quantum sensing and quantum imaging. Quantum sensing can provide systems with unprecedented accuracy and sensitivity by utilizing its quantum properties. Quantum imaging uses entangled photon states to capture information, enabling signal‐to‐noise ratio and resolution that surpass the limits of classical imaging. The synergistic integration of weak measurement with quantum sensing and imaging paves the way for next‐generation technologies with practical value, significantly advancing frontiers of precision metrology and imaging science. This review elucidates the fundamental theory of weak value amplification and comprehensively discusses the performance of weak measurement strategies in quantum sensing and imaging frameworks, highlighting both classical techniques and emerging quantum applications. It covers four main directions: nanostructure, 2D atomic crystal, biochemistry, and optical imaging, including from structural parameters characterization to chemical reaction sensing to nonlocal weak measurement microscopy. This work aims to discuss recent advances in weak measurement applications for quantum sensing and imaging platforms, while outlining future development opportunities arising from the convergence of these three fields.
Recent years have witnessed a growing interest in understating the limitations imposed by quantum noise in precision measurements and devising techniques to reduce it. The attention is currently turning to the simultaneously estimation of several parameters of interest, driven by its promising potential across a wide range of sensing applications as well as fueled by experimental progress in various optical and atomic platforms. Here, we provide a comprehensive overview of key research directions in multiparameter quantum sensing and metrology, highlighting both opportunities and challenges. We introduce the basic framework, discuss ultimate sensitivity bounds, optimal measurement strategies, and the role of quantum incompatibility, showing important differences with respect to single-parameter estimation. Additionally, we discuss emerging experimental implementations in distributed quantum sensing, including cutting-edge optimization techniques. This review aims to bridge the gap between theory and experiments, paving the way for the next-generation of quantum sensors and their integration with other quantum technologies.
Abstract Even though weak measurements and weak value amplification (WVA) are founded on the principles of quantum mechanics and quantum measurements, these have found widespread applications in optics due to their inherent origin in wave interference. Besides their use in addressing foundational questions of quantum mechanics or for resolving quantum paradoxes, weak measurements and WVA have thus been used for numerous metrological applications, e.g., quantification of small optical beam displacement, tiny angular rotation, determination of extremely small phase shifts, spectral shifts, unraveling weak fundamental optical effects, improved optical imaging, amplifying weak signal and extracting small physical parameters and so forth. In this review, after providing the mathematical foundation of weak measurement and WVA, some of the metrological applications of weak measurements in the classical optics domain are briefly summarized, and the controversies and debates on the potential advantages of WVA in the estimation and detection of weak signal are discussed, and the interferometric philosophy of WVA is elucidated. The experimental weak measurement and WVA schemes in the domain of quantum optics are also discussed and highlighted the new perspectives and emerging trends of weak measurements in both the classical and quantum optics domain and their prospects in the development of next‐generation ultra‐sensitive optical devices.
Quantum imaging is an emerging field based on quantum mechanics and imaging technology, capable of unique capabilities in resolution, sensitivity, and information processing. An extensive review of the concepts, methods, and uses of quantum imaging is given in this chapter. The main ideas of quantum mechanics that are relevant to imaging, including superposition, entanglement, and quantum measurement, are introduced in this chapter. Following this, the various quantum imaging techniques, including quantum entanglement imaging, ghost imaging, and quantum lithography, illuminating their operational mechanisms and advantages over classical methods, are explored. The role of advanced photonic systems, single-photon detectors, and quantum dots in enhancing image quality are discussed. Additionally, the incorporation of quantum computing and machine learning with quantum imaging is examined, highlighting how these interdisciplinary approaches are pushing the boundaries of what can be visualized and analysed. Quantum imaging applications are varied, groundbreaking, and innovative, ranging from medical diagnostics and biological imaging to quantum communication and fundamental physics research. By harnessing the exclusive properties of quantum states, these applications achieve higher precision and new capabilities that classical imaging techniques cannot match. The challenges and future directions of quantum imaging, considering both the technical hurdles and the potential for groundbreaking discoveries, are discussed as well. In a nutshell, the chapter aims to offer the readers an in-depth insight into quantum imaging, its current state, and its future prospects by providing a holistic view of how quantum imaging is composed to revolutionize various scientific and technological fields.
Background: High-precision sensing is vital for modern technology, yet conventional sensors are fundamentally constrained by classical noise limits. Quantum sensing leverages principles of quantum mechanics, such as superposition and entanglement, to overcome these barriers, offering unprecedented sensitivity. This review comprehensively analyzes the current state of quantum sensor technology, focusing on its underlying physical principles, emerging applications, and the pathway toward industrial maturation.Methods: We synthesize findings from key research areas, detailing the foundational quantum systems like Nitrogen-Vacancy (NV) centers in diamond and advanced optical techniques. The paper reviews the theoretical methods used to achieve sub-shot-noise performance and discusses the system-level engineering challenges necessary for practical deployment, particularly concerning microwave control and optical readout. We also assess the current landscape of standardization efforts for quantum technologies.Results: Significant breakthroughs are highlighted in both biomedical and environmental sensing. Applications range from tracking cellular redox-status using electron-paramagnetic resonance to ultra-sensitive salinity measurements. The analysis confirms that quantum sensing provides superior resolution compared to classical counterparts, unlocking new capabilities in in-vivo and real-time monitoring.Discussion: While offering transformative potential, widespread adoption faces hurdles, including the maintenance of quantum coherence in ambient environments and the high cost and complexity of current instrumentation. Future efforts must focus on miniaturization, integration with classical systems, and standardized fabrication protocols. Quantum sensing represents the next-generation technological paradigm for metrology.
Quantum imaging is emerging as a transformative approach for biomedical applications, applying nonclassical properties of light, such as entanglement, squeezing, and quantum correlations, to overcome fundamental limits of conventional techniques. These methods promise superior spatial resolution, enhanced signal-to-noise ratios, improved phase sensitivity, and reduced radiation dose, for potentially safer and more precise imaging for delicate biological samples. Here, we present an overview of quantum optical biomedical imaging technologies as well as quantum-inspired imaging methods, including quantum optical coherence tomography, quantum optical microscopy, ghost imaging, multi-parameter quantum imaging, and imaging with quantum-grade cameras. We describe the operating principles, biomedical applications, and unique advantages of each approach, along with the specific challenges for their translation into real-life practice. This review aims to guide future research toward advancing quantum imaging from experimental demonstrations to impactful biomedical tools.
Weak measurement refers to a type of quantum measurement that disturbs the system very little. In the framework of weak measurement, Aharonov, Albert, and Vaidman introduced the concept of postselection and thereby defined the weak value. In recent research, weak-value measurement (WVM) has offered a novel perspective for studying intricate problems in quantum mechanics, leading to many conceptual breakthroughs. More importantly in practice, WVM has shown an unprecedented impact on precision sensing. In this review, we begin by presenting the fundamental theory of WVM based on quantum parameter estimation, from which the effects of weak-value amplification and weak-coupling amplification can be derived. The two effects can significantly improve the precision in various sensing schemes based on WVM. We point out the technical advantages that enable the WVM schemes to outperform the conventional ones under the same measurement conditions. Notably, the capability of information compression is underscored, which is garnering increasing attention in the field of quantum metrology. This review aims to show the possibility for broadening the application of WVM to address more critical problems, and on the other hand, for leveraging its advantages to accomplish tasks that are currently unattainable, such that WVM could play a more important role in the future of precision sensing.