Quantum radar represents a major shift in sensing by leveraging quantum correlations and entanglement to detect targets beyond the line of sight in complex environments. Unlike classical radar, which suffers severe performance loss in dense urban areas due to multipath effects, clutter, and noise, quantum radar uses biphoton correlations to preserve strong detection sensitivity even under heavy interference. This chapter presents a comprehensive review of quantum radar systems, focusing on NLOS functionality. It describes key concepts such as biphoton generation through spontaneous parametric down-conversion, quantum illumination methods, and optimal detection strategies. Practical implementations using cryogenic superconducting nanowire single-photon detectors and AI-based signal processing are also discussed. The role of quantum radar in future 6G integrated sensing and communication frameworks is explored, highlighting uses in autonomous vehicle safety and smart city monitoring. Simulation studies show detection rates above 95% at a 1 km NLOS distance, with up to a tenfold SNR improvement over classical systems, while experiments demonstrate more than 20 dB of noise reduction. The chapter concludes by addressing ongoing challenges like decoherence, scalability, and standardization, and outlines a pathway toward deployable quantum radar technologies by 2030 for Industry 5.0 applications.
Quantum radar represents a major shift in sensing by leveraging quantum correlations and entanglement to detect targets beyond the line of sight in complex environments. Unlike classical radar, which suffers severe performance loss in dense urban areas due to multipath effects, clutter, and noise, quantum radar uses biphoton correlations to preserve strong detection sensitivity even under heavy interference. This chapter presents a comprehensive review of quantum radar systems, focusing on NLOS functionality. It describes key concepts such as biphoton generation through spontaneous parametric down-conversion, quantum illumination methods, and optimal detection strategies. Practical implementations using cryogenic superconducting nanowire single-photon detectors and AI-based signal processing are also discussed. The role of quantum radar in future 6G integrated sensing and communication frameworks is explored, highlighting uses in autonomous vehicle safety and smart city monitoring. Simulation studies show detection rates above 95% at a 1 km NLOS distance, with up to a tenfold SNR improvement over classical systems, while experiments demonstrate more than 20 dB of noise reduction. The chapter concludes by addressing ongoing challenges like decoherence, scalability, and standardization, and outlines a pathway toward deployable quantum radar technologies by 2030 for Industry 5.0 applications.
Quantum radar represents a major shift in sensing by leveraging quantum correlations and entanglement to detect targets beyond the line of sight in complex environments. Unlike classical radar, which suffers severe performance loss in dense urban areas due to multipath effects, clutter, and noise, quantum radar uses biphoton correlations to preserve strong detection sensitivity even under heavy interference. This chapter presents a comprehensive review of quantum radar systems, focusing on NLOS functionality. It describes key concepts such as biphoton generation through spontaneous parametric down-conversion, quantum illumination methods, and optimal detection strategies. Practical implementations using cryogenic superconducting nanowire single-photon detectors and AI-based signal processing are also discussed. The role of quantum radar in future 6G integrated sensing and communication frameworks is explored, highlighting uses in autonomous vehicle safety and smart city monitoring. Simulation studies show detection rates above 95% at a 1 km NLOS distance, with up to a tenfold SNR improvement over classical systems, while experiments demonstrate more than 20 dB of noise reduction. The chapter concludes by addressing ongoing challenges like decoherence, scalability, and standardization, and outlines a pathway toward deployable quantum radar technologies by 2030 for Industry 5.0 applications.
Quantum radar has emerged as a promising sensing paradigm that exploits quantum resources, including entanglement and quantum correlations, to enhance target detection in noisy and lossy environments. Although entanglement generated by superconducting devices such as Josephson parametric amplifiers, Josephson parametric converters, and Josephson traveling-wave parametric amplifiers is rapidly degraded under realistic propagation conditions, the remaining quantum correlations can still provide a measurable detection advantage through the principles of quantum illumination. This review presents a comprehensive engineering perspective on quantum radar, covering the theoretical foundations of quantum illumination, microwave entanglement generation, electro-optomechanical quantum transducers, atmospheric channel effects, cryogenic receiver architectures, and digital signal-processing techniques. Recent microwave experimental demonstrations are also reviewed, highlighting the transition from theoretical concepts to laboratory-scale implementations. Collectively, these developments demonstrate that microwave quantum radar is evolving toward practical sensing architectures while emphasizing the engineering challenges that must be addressed before real-world deployment.
Quantum radar systems leverage entangled photon pairs to detect and identify targets in noisy or cluttered environments with sensitivity beyond classical limits. By transmitting one photon of an entangled pair toward a distant object while retaining its partner locally, the system exploits quantum correlations to improve signal discrimination, reduce noise susceptibility, and enhance detection probability. This paper outlines the physical principles, operational architecture, and performance advantages of entanglement‑based illumination, providing a clear foundation for future quantum‑enhanced sensing technologies.(If you want it shorter, longer, or more formal, tap: shorter paragraph, longer paragraph, more formal)
Quantum radars and lidars are a novel, much-discussed, and rapidly evolving field of quantum science and technology, promising remarkable advantages in such basic tasks as target detection, ranging, and recognition. Quantum radars and lidars have already moved from the realm of theoretical considerations toward experiments, green, and as is the case for lidars, toward practical applications. Here we review the underlying concepts and present the basic configurations of quantum radars and lidars based on photonic entanglement and single-photon detection. We also briefly discuss the methods of producing entangled photons, such as spontaneous parametric down conversion (SPDC), spontaneous four-wave mixing, Josephson parametric amplifiers (JPAs), and quantum antennas. We show that quantum technologies open promising avenues toward the enhancement of signal-to-noise ratio (SNR) and overcoming the Rayleigh limit in radar and lidar systems.
This article presents a comprehensive analysis of two classes of quantum radars, including quantum direct-detection and quantum-entangled noise radars. In the first case, inspired by the well-established concept of single-photon LiDARs, we investigated the performance of single-photon radars, in which state-of-the-art single microwave-photon detectors are employed to enhance the detection sensitivity and enable the detection of weaker signals. We derived analytical expressions for the maximum detection range of both classes of quantum radars in terms of the Lambert W function, by considering all relevant system, target, and environmental parameters. Our formulation facilitates direct comparison of noise radars with direct-detection radars and suggests that a quantum-entangled noise radar can be regarded as an enhanced direct-detection radar with an effective threshold signal-to-noise ratio. Furthermore, we applied this framework to classical-correlated noise radars and defined the parameter range enhancement factor (REF) to quantify the superiority of quantum-entangled noise radars over their classical counterparts. Moreover, we introduced a rule-of-thumb for approximating the REF. We also examined the influence of limitations imposed by various microwave detection technologies. Our analysis shows that the conventional antennas limit the potential benefits of quantum-entangled noise radar systems. We also demonstrated that the optimal detection method for these radars is a microwave detector based on a quantum transducer combined with a single optical-photon detector. We showed that, with the current technology, implementing a quantum-entangled noise radar with the maximum detection range on the order of few kilometers is possible. Finally, we explored the potential applications of quantum-entangled noise radars.
Quantum radar represents a promising advancement over classical radar systems by exploiting quantum mechanical phenomena such as entanglement and quantum measurement to overcome fundamental detection limitations. This paper reviews the evolution of radar technology from conventional radar frequency systems to quantum radar architectures, with emphasis on sensitivity enhancement and detection of RF-stealth targets for military defense applications. Classical radar parameters such as radar range, transmitted power and cross section are revisited and extended to their quantum analogues. The role of entangled single photon sources in improving detection performance under high noise and jamming environments is discussed. Context of microwave quantum radar is reviewed along with photonic implementations. This paper further highlights the importance of quantum measurement theory, including system-apparatus entanglement, density matrix formalism and wave function collapse in extracting information from quantum radar systems. Although significant experimental challenges remain, recent advances indicate strong potential for future development of quantum radar in next generation defense and surveillance systems.