Abstract This review provides a comprehensive overview of the key materials underpinning quantum technologies, including two-dimensional system (2D), superconducting materials, and nitrogen-vacancy (NV − ) centers in diamond. Particular emphasis is placed on their roles in quantum sensing, communication, and qubit design. Quantum sensors, such as atomic vapor magnetometers, solid-state spin sensors, and superconducting quantum interference devices (SQUID) circuits, have become essential tools for measuring magnetic fields and detecting physical phenomena at extremely small scales. These technologies, with diverse applications ranging from medicine and geophysics to biotechnology and materials science, offer new opportunities for detecting and measuring nanoscale phenomena and are poised to play a key role in the future of quantum technologies.
Abstract This review provides a comprehensive overview of the key materials underpinning quantum technologies, including two-dimensional system (2D), superconducting materials, and nitrogen-vacancy (NV − ) centers in diamond. Particular emphasis is placed on their roles in quantum sensing, communication, and qubit design. Quantum sensors, such as atomic vapor magnetometers, solid-state spin sensors, and superconducting quantum interference devices (SQUID) circuits, have become essential tools for measuring magnetic fields and detecting physical phenomena at extremely small scales. These technologies, with diverse applications ranging from medicine and geophysics to biotechnology and materials science, offer new opportunities for detecting and measuring nanoscale phenomena and are poised to play a key role in the future of quantum technologies.
Quantum sensors encompass a diverse class of devices that exploit quantum coherence to detect weak or nanoscale signals. As their behavior is tied to physical constants, quantum sensors can achieve accuracy, repeatability, and precision approaching fundamental limits [1, 2]. As a result, these sensors have shown utility in a wide range of applications in both science and engineering leading to innovations. Among many solid-state spin systems, nitrogen-vacancy (NV) centers in diamonds have attracted considerable attention as a leading platform in many fields of quantum technologies, from quantum sensing to information processing and communication applications. They have superior physical properties, and their quantum coherence is preserved even at room temperature. The energy levels of NV centers are sensitive to magnetic fields, electric fields, strain, and temperature, and the spatial resolution is scalable from nanometers to millimeters. Therefore, diamond quantum sensors are distinctive sensors with multimodality and span scalable application fields. To realize an ideal quantum sensor for applications, the technical challenges in the sensor materials and the quantum control techniques, such as coherent microwave spin manipulation, effective optical spin-state initialization, and readout, have been developed. This chapter briefly explains the sensing principle using NV centers and then introduces sensor systems for biomedical applications, and monitoring of batteries for electric vehicles and internal power devices.
Quantum sensors and metrology harness quantum phenomena—such as superposition, entanglement, and squeezing—to achieve precision measurements beyond classical limits. This review presents an overview of the fundamental principles underlying quantum sensing, including quantum coherence, entanglement-assisted measurement, and quantum-enhanced interferometry. Various quantum sensor platforms are discussed, including atomic clocks, nitrogen-vacancy (NV) center magnetometers, superconducting quantum interference devices (SQUIDs), optomechanical sensors, and trapped-ion systems. We explore their operational mechanisms, performance metrics, and technological implementations. Comparative analyses highlight sensitivity, spatial resolution, bandwidth, and environmental robustness. Advances in materials, control techniques, and hybrid architectures are examined, and emerging applications in navigation, geophysics, medical imaging, and fundamental physics are reviewed. Finally, future prospects for scalable and robust quantum metrology are discussed.
This monograph presents the emerging field of second-generation quantum sensing, which leverages phenomena such as superposition and entanglement, thereby offering measurement sensitivities far surpassing classical methods. In our discussion, we emphasize its potential to revolutionize various scientific and technological domains. Starting with a foundational overview of quantum sensors, distinguishing them from quantum computing and communication technologies, we then highlight the relative maturity of quantum sensing, especially in room-temperature operations, which positions it closest to market adoption. The main part of the monograph is dedicated to solid-state defects, particularly nitrogen-vacancy (NV) centers in diamond, which have emerged as promising candidates for scalable quantum sensors. The unique optical and spin properties of NV centers are explored in detail, emphasizing their possible applications in fields such as biomedical imaging, materials science, and semiconductor inspection. We delve into the technical aspects of integrating NV centers with conventional electronic and photonic systems, discussing the challenges and innovations in electronic interface circuits, photonic integration, and system-level integration technologies. Additionally, we examine gas-based quantum sensors, particularly those utilizing Rydberg atoms, which offer high precision due to their long coherence times. The challenges of integrating gas-based sensors, compared to their solid-state counterparts, are also briefly discussed. Overall, the monograph underscores the potential of second-generation quantum sensors, particularly those based on NV centers, to be the first scalable, high-volume quantum devices on the market, with applications spanning various fields due to their high sensitivity and room-temperature operation.
The advancement of chemistry and materials science relies on transformative analytical tools which can overcome the sensitivity, spatial resolution, and throughput limitations of conventional techniques. This review explores the application of quantum sensors - specifically optically pumped magnetometers (OPMs) and nitrogen-vacancy (NV) centers in diamond - as robust platforms for molecular and materials analysis. We contrast the extreme magnetic sensitivity of macroscopic OPM ensembles with the atomic-scale resolution and multimodal capabilities of solid-state NV centers. We highlight their deployment in zero- to ultralow-field and nanoscale NMR spectroscopy, real-time reaction monitoring, and transient radical and pH detection. Furthermore, we discuss their integration into high-throughput chemical assays and non-destructive materials diagnostics, such as operando battery monitoring. With the ongoing commercialization of these technologies and advances in quantum-enhanced sensitivities, quantum sensors are poised to routinely address complex real-world analytical challenges.
Quantum sensing is a quantum technology for ultrasensitive detection, which is particularly useful for sensing weak signals at the nanoscale. Nitrogen vacancy centers in diamond, thanks to their superb quantum coherence under ambient conditions and the stability of the material in extreme and complicated environments, have been demonstrated as promising quantum probes in multi-parameter sensing. Their spin properties make them particularly sensitive to magnetic fields, but they are insensitive to temperature, electric field, pressure, etc., and even immune to some bio-parameters (e.g., pH and glucose concentration). Recently, hybrid quantum sensing has emerged as a promising avenue for further enhancing the capabilities of diamond sensors. Different techniques can potentially improve the sensitivity, range of detectable parameters, and sensing frequencies of diamond sensors. This review provides an overview of hybrid quantum sensing using diamond. We first give a brief introduction to quantum sensing using diamond, and then review various hybrid sensing schemes that have been developed to enhance the sensing capabilities of diamond sensors. Finally, the potential applications and challenges associated with hybrid quantum sensing in diamond are discussed.