Quantum metrology, being a branch of modern metrology, is a study that provides highresolution and very sensitive measurement of physical parameters by explaining the properties ofphysical systems in terms of quantum theory. By developing new measurement methods, thisfield demonstrates higher accuracy than the same measurements performed in a classical framework.
Quantum metrology, being a branch of modern metrology, is a study that provides highresolution and very sensitive measurement of physical parameters by explaining the properties ofphysical systems in terms of quantum theory. By developing new measurement methods, thisfield demonstrates higher accuracy than the same measurements performed in a classical framework.
The statistical error is ineluctable in any measurement. Quantum techniques, especially with the development of quantum information, can help us squeeze the statistical error and enhance the precision of measurement. In a quantum system, there are some quantum parameters, such as the quantum state, quantum operator, and quantum dimension, which have no classical counterparts. So quantum metrology deals with not only the traditional parameters, but also the quantum parameters. Quantum metrology includes two important parts: measuring the physical parameters with a precision beating the classical physics limit and measuring the quantum parameters precisely. In this review, we will introduce how quantum characters (e.g., squeezed state and quantum entanglement) yield a higher precision, what the research areas are scientists most interesting in, and what the development status of quantum metrology and its perspectives are.
Quantum metrology leverages the unique properties of quantum systems to enhance parameter estimation beyond classical limits. In this short review, we introduce the core concepts of quantum metrology, with a particular focus on its extension to multi-parameter estimation. We begin by outlining the foundational principles of quantum metrology and explore how quantum criticality can enhance measurement precision — especially near quantum phase transitions, where systems exhibit heightened sensitivity to external perturbations. Next, we consider the framework of multi-parameter quantum critical metrology, in which the simultaneous estimation of multiple parameters near criticality can lead to further improvements in accuracy. Finally, we discuss measurement-induced phase transitions, a phenomenon emerging in the context of continuous quantum measurements that introduces non-Hermitian dynamics and fundamentally alters the system’s behavior. This review provides a concise overview of these key developments and highlights their significance for future progress in quantum sensing technologies.
The measurement of physical quantities and measurement units standard promote the development of metrology. Especially, the developments of laser interference and atomic frequency standard bring a revolutionary leap for metrology. Many precision measurement techniques have been proposed and experimentally demonstrated, such as gravitational wave measurements and laser gyroscopes based on laser interferometry, and atomic clocks and atomic gyroscopes based on the atom interferometry. Recently, a new branch of science, quantum metrology, has grown up to further explore and exploit the quantum techniques for precision measurement of physical quantities.#br#This paper will focus on recent developments in quantum metrology and interference based on coherence and correlation of light and atom. Firstly, we briefly review the development of metrology. Then, we introduce our own researches in recent years, including quantum-correlation SU(1,1) optical interferometer based on four wave mixing process in atomic vapor and the atom-light hybrid interferometer based on Raman scattering in atomic vapor.#br#Interferometer is a powerful tool to measure physical quantities sensitive to the inference wave with high precision, and has been widely used in scientific research, industry test, navigation and guidance system. For example, the laser interferometer is able to measure optical phase sensitive quantities, including length, angular velocity, gravitational wave and so on. Meanwhile, the atom interferometer is sensitive to the change of atomic phase caused by the light, gravity, electric and magnetic fields. As a new type of interferometry, the atom-light hybrid interferometer, is sensitive to both the optical phase and atomic phase. Furthermore, SU(1,1) interferometer and nonlinear atom-light hybrid interferometer have the ability to beat the standard quantum limit of phase sensitivity. Quantum interference technology, whose phase measurement accuracy can break through the limit of standard quantum limit, is the core of quantum metrology and quantum measurement technology.
Quantum mechanics has profoundly reshaped our knowledge of the physical world: a deep comprehension of the quantum nature of matter yielded to the so-called first quantum revolution, enabling transformative technologies ranging from lasers to semiconductor de- vices, being at the heart of the digital revolution characterizing the second half of the XXth century. Furthermore, the capability of manipulating and controlling individual quantum systems enabled a totally different working paradigm, obeying the logic im- posed by quantum physics, paving the way, at the end of the XXth and the beginning of the XXIst century, for the second quantum revolution. Modern quantum technologies, including quantum computation, quantum simulation, quantum metrology and quantum communication rely on peculiar quantum phenomena, such as superposition, entangle- ment and coherence to perform tasks beyond classical capabilities. This thesis proposes quantum metrology as a unifying conceptual and methodological framework to investigate problems lying at the intersection of fundamental quantum physics and quantum information science. More in detail, it addresses theoretical and experimental protocols to certify the presence of quantum correlations (namely, quantum steering), as well as to design secure sensing in quantum networks under realistic assump- tions. Moreover, it also suggest how tunable-strength measurement-based strategies can be used to extract information from complex systems even in seemingly inaccessible sce- narios. Overall, this thesis proposes quantum metrology as a framework through which the purest nature of information can be probed, certified and secured at the most fundamental level.
Abstract Quantum metrology pursues the physical realization of higher‐precision measurements to physical quantities than the classically achievable limit by exploiting quantum features, such as entanglement and squeezing, as resources. It has potential applications in developing next‐generation frequency standards, magnetometers, radar, and navigation. However, the ubiquitous decoherence in the quantum world degrades the quantum resources and forces the precision back to or even worse than the classical limit, which is called the no‐go theorem of noisy quantum metrology and greatly hinders its applications. Therefore, how to realize the promised performance of quantum metrology in realistic noisy situations attracts much attention in recent years. The principle, categories, and applications of quantum metrology are reviewed. Special attention is paid to different quantum resources that can bring quantum superiority in enhancing sensitivity. Then, the no‐go theorem of noisy quantum metrology and its active control under different kinds of noise‐induced decoherence situations are introduced.
This paper proposes a novel methodology for real-time algorithm verification utilizing quantum metrology principles. The core concept involves employing entangled states to conduct highly precise measurements of algorithm execution, comparing these measurements against a rigorously defined, verifiable baseline. Traditional algorithm verification methods often rely on simulation and testing, which can be computationally expensive and may not fully capture the nuances of a system's behavior under all conditions. This approach offers a direct, high-precision measurement of algorithm performance, potentially mitigating these limitations. We outline the theoretical framework, focusing on the use of quantum sensitivity to detect subtle deviations from expected behavior. The key advantage lies in the ability to achieve a level of accuracy unattainable through classical methods, offering a robust validation process suitable for complex algorithms, particularly those involved in quantum computing and related fields. The paper details the mathematical foundation, including the Heisenberg Uncertainty Principle and its application to algorithm verification, and presents a framework for quantifying the achievable accuracy. Further research directions are explored, including the integration of this technique with existing verification protocols and the development of tailored entangled state designs.