Quantum sensing, utilizing quantum techniques to extract key information of a quantum (or classical) system, is a fundamental area in quantum science and technology. For quantum sensors, a basic capability is to uniquely infer unknown parameters in a system based on measurement data from the sensors. In this paper, we investigate the capability of a class of quantum sensors for a spin-12 chain system with unknown parameters. The sensors are composed of qubits which are coupled to the object system and can be initialized and measured. We consider the capability of the single- and two-qubit sensors and show that the capability of single-qubit quantum sensors can be enhanced by adding an extra qubit into the sensor under a certain initialization and measurement setting.
Quantum sensing, utilizing quantum techniques to extract key information of a quantum (or classical) system, is a fundamental area in quantum science and technology. For quantum sensors, a basic capability is to uniquely infer unknown parameters in a system based on measurement data from the sensors. In this paper, we investigate the capability of a class of quantum sensors for a spin-12 chain system with unknown parameters. The sensors are composed of qubits which are coupled to the object system and can be initialized and measured. We consider the capability of the single- and two-qubit sensors and show that the capability of single-qubit quantum sensors can be enhanced by adding an extra qubit into the sensor under a certain initialization and measurement setting.
Recent breakthroughs in quantum technology pave the way for extensive utilization of higher-dimensional quantum systems, which outperform their qubit counterparts in terms of capabilities and versatility. We present a framework for accurately predicting weak external magnetic fields using a higher-dimensional many-body quantum probe. We demonstrate that dimension serves as a valuable resource for quantum sensing when a transverse spin-s Ising chain interacts locally with a magnetic field whose strength has to be determined. We observe the distinct performance of sensors for spin chains with half-integer and integer spins. Furthermore, we highlight that the time duration appropriate for quantum-enhanced sensing increases with the increase of dimension. Additionally, we observe that, in addition to nearest-neighbor interactions, incorporating interactions between the next nearest-neighbor sites increases sensing precision, particularly for spin chains with integer spins. We also prove the dimensional-dependence of the bound on quantum Fisher information which provides the limit on the precision in estimating parameters.
Abstract Quantum sensors can enable the simultaneous and precise measurement of multiple physical parameters, facilitating the development of dual-sensing techniques. In this paper, we report on the simultaneous multi-parameter quantum sensing of temperature and magnetic field based on a quantum sensor consisting of a two-qubit Heisenberg XYZ chain, which enables joint quantum thermometry and magnetometry. Qubits interact via ferromagnetic and antiferromagnetic couplings, and are in thermal equilibrium with a heat bath in the presence of an external magnetic field. Specifically, the sensor’s response to perturbations, like temperature and magnetic field changes, is analyzed through quantum Fisher information (QFI), providing a measure of the sensing precision. We investigate the effects of different types of inter-qubit couplings and external magnetic fields on the accuracy of multi-parameter estimation. Our results demonstrate that simultaneous multi-parameter estimation improves the speed of information extraction and processing, accuracy, and sensitivity of our quantum sensor. This work provides a promising avenue for developing high-performance multiparameter quantum sensors with potential applications in various fields, including materials science, biomedicine, environmental monitoring, aerospace, industrial production, and other fields.
This paper explores the development and potential of quantum sensors utilizing multi-variable measurement. The core concept revolves around leveraging the quantum coherence inherent in quantum sensors to simultaneously measure multiple physical quantities. This is achieved through the design of entangled sensor networks, where the state of one sensor provides information about the states of all interconnected sensors. This approach represents a significant advancement in the field of quantum sensing, offering the possibility of enhanced sensitivity and reduced measurement complexity for applications requiring the simultaneous determination of multiple parameters. The theoretical framework presented here outlines the fundamental principles and explores potential architectures, highlighting the advantages and challenges associated with this technology. We focus on the mathematical underpinnings of entangled sensor systems and the extraction of information from correlated quantum states. ---
We introduce a general model for a network of quantum sensors, and we use this model to consider the question: when do correlations (quantum or classical) between quantum sensors enhance the precision with which the network can measure an unknown set of parameters? We rigorously answer this question for a range of practically important problems. When each sensor in the network measures a single parameter, we show that correlations between sensors cannot increase the estimation precision beyond what can be achieved with an uncorrelated scheme, regardless of the particular details of the estimation problem in question. We also consider the more general setting whereby each sensor may be used to measure multiple parameters, e.g., the three spatial components of a magnetic field. In this case, we show that correlations between sensors can only provide, at best, a small constant precision enhancement, over uncorrelated estimation techniques. Finally, we consider optimizing the network for measuring a single linear function of the unknown parameters, e.g., the average of all of the parameters. Here quantum correlations between the sensors can provide a significant precision enhancement over uncorrelated techniques, and this enhancement factor scales with the number of sensors. To illustrate the broad implications of this work, we apply our results to a wide range of estimation problems of practical interest, including multi-mode optical interferometry, networks of atomic sensors, and networks of clocks. Our findings shed light on a number of results in the literature, provide a rigorous general framework for future research on networked quantum sensors, and have implications for both quantum multi-parameter estimation theory, and quantum sensing technologies.
The applications of spin-based quantum sensors to measurements probing fundamental physics are surveyed. Experimental methods and technologies developed for quantum information science have rapidly advanced in recent years, and these tools enable increasingly precise control and measurement of spin dynamics. Theories of beyond-the-Standard-Model physics predict, for example, symmetry violating electromagnetic moments aligned with particle spins, exotic spin-dependent forces, coupling of spins to ultralight bosonic dark matter fields, and changes to the local environment that affect spins. Spin-based quantum sensors can be used to search for these myriad phenomena, and offer a methodology for tests of fundamental physics that is complementary to particle colliders and large scale particle detectors. Areas of technological development that can significantly enhance the sensitivity of spin-based quantum sensors to new physics are highlighted.
In the later years, the quantum sensor is considered to be one of the key techniques for the next generation of sensors and provides a new paradigm for sensing technology. Within the realm of quantum technology, Quantum sensing is a rapidly growing research subject that focuses on spin qubits, trapped ions, and flux qubits as the most prevalent platforms. Quantum sensors and quantum sensing techniques based on integrated quantum photonics serve as the foundation for the realization of these next-generation sensing. The paper presents a brief review of quantum sensor techniques, applications, and recent advancements in the domain of quantum sensors over the last few years.