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.
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.
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.
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 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.
This paper presents a study on quantum radar technology developments, design Consideration for its integration, and quantum radar cross-section, QRCS based on quantum electrodynamics and interferometric considerations. Quantum radar systems supported by quantum measurement can fulfill not only conventional target detection and recognition tasks but are also capable of detecting and identifying the RF stealth platform and weapons systems. The development of radar technology is of the utmost importance in many avenues of research. The concept of a quantum radar has been proposed which utilizes quantum states of photons to establish information on a target at a distance. A photon, or a little cluster of photons, is distributed towards the target. The photons are absorbed and reemitted from the target and into the receiver. The measurement process may be executed in two alternative ways. One can perform an interferometric measurement (or phase measurement) on the photon, or one can simply count the number of photons that return. the previous method is named Interferometric Quantum Radar, and therefore the latter method is termed Quantum Illumination. For either of those methods, one can use stationary quantum states of photons or use entangled states. Its been shown that entangled states provide the most effective possible boost in resolution, achieving within the ideal case. The benefit of using quantum states is that they exhibit extra degrees of correlation by which to get information compared to classical methods. These extra correlations (called quantum correlations) serve to boost the resolution and signal/noise (SNR) that may be achieved within the radar system.
This paper provides a brief introduction of the current state of quantum radar (QR) technology development, focusing on the experimental methods used for modifying QR in a laboratory setting. We delve into the foundational principles of quantum electrodynamics and consider interferometric aspects. Quantum radar systems, empowered by quantum measurements, extend their capabilities beyond conventional target detection and recognition, encompassing the detection and identification of RF stealth platforms and advanced weapons systems. Quantum technology is gaining paramount significance in various research domains, with the emergence of the concept of quantum radar, which leverages the quantum states of photons to extract information from distant targets. The mechanism involves dispatching photons, or photon clusters, toward the target, whereupon they are absorbed and subsequently re-emitted. The crucial measurement process can be executed in two distinct manners. One approach entails an interferometric measurement, often referred to as phase measurement, conducted on the photons, while the alternative method involves the straightforward quantification of returning photons. These methods are respectively known as Interferometric QR and Quantum Illumination (QI). In both approaches, one can opt to employ stationary quantum states of photons or harness entangled states. Extensive research has demonstrated that the use of entangled states yields the most significant resolution enhancement, achieving optimal results under ideal conditions. Quantum states offer a substantial advantage by virtue of their inherent correlations, referred to as quantum correlations, which augment both resolution and signal-to-noise ratio (SNR) in the radar system. This paper explores the intricacies of these advancements in quantum radar technology, shedding light on the underlying principles and experimental methodologies.