The article “Quantum Radars and Lidars: Concepts, Realizations, and Perspectives,” by Gregory Slepyan, Svetlana Vlasenko, Dmitri Mogilevtsev, and Amir Boag is one that stretches the imaginations of conventional practitioners of radar technology. The quantum advantage that quantum sensing will deliver is too great to be ignored, even though naysayers may not agree on this path. Also, the knowledge base in quantum technologies is incredibly thin, and, hopefully, this article will spur more engineers and scientists to take up the challenge of working in this area, sharing their experience and knowhow as well as expanding the knowledge base. We have seen the recent exciting growth in quantum computing technology, and we wish for the same excitement in quantum sensing technology. The ability to use entangled photon pairs to enhance the detection of weak photons will be beneficial to other applications, such as quantum sensing and quantum imaging in biomedical engineering and health care. Entangled photon pairs are also useful in quantum communication.
The article “Quantum Radars and Lidars: Concepts, Realizations, and Perspectives,” by Gregory Slepyan, Svetlana Vlasenko, Dmitri Mogilevtsev, and Amir Boag is one that stretches the imaginations of conventional practitioners of radar technology. The quantum advantage that quantum sensing will deliver is too great to be ignored, even though naysayers may not agree on this path. Also, the knowledge base in quantum technologies is incredibly thin, and, hopefully, this article will spur more engineers and scientists to take up the challenge of working in this area, sharing their experience and knowhow as well as expanding the knowledge base. We have seen the recent exciting growth in quantum computing technology, and we wish for the same excitement in quantum sensing technology. The ability to use entangled photon pairs to enhance the detection of weak photons will be beneficial to other applications, such as quantum sensing and quantum imaging in biomedical engineering and health care. Entangled photon pairs are also useful in quantum communication.
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.
Photons are very promising resources for the whole field of quantum information processing. Bulk optics are currently not suitable for the realization of complex quantum optical schemes due to several drawbacks. The ongoing miniaturization of photonic structures due to the availability of sophisticated nanofabrication has provided huge opportunities for physical research of novel phenomena in nanophotonic systems and quantum technological applications. These include quantum information processing such as quantum computing, quantum communication, quantum metrology, and quantum sensing. Quantum communication is already quite advanced with several quantum key distribution (QKD) systems commercially available offering absolute security. Photonic quantum technologies are enabling breakthroughs in experimental tests of quantum physics and are close to practical applications of quantum technologies in imaging, secure communications, ultrasensitive metrology and quantum computing. There are several advantages to encoding a quantum bit onto a photon: the preparation and manipulation of single photons is easy, and the photonic qubit is a natural candidate for quantum imaging and communications. Furthermore, the qubit can be encoded in various degrees of freedom such as on the position, phase, time-bin, energy, angular momentum, polarization of the photon—or a combination of these. This flexibility leads to enormous opportunities for scientific exploration and in practical applications. This special issue on “Photonic Quantum Technologies” presents selected papers on photonic quantum systems from leading groups in the world. The articles represent a flavor of the cutting-edge research that is going on in this area. The studied material systems range from molecules to semiconductor quantum emitters. A major challenge is the design of telecom photon emitters with high efficiency, good yield, spectral purity, stability and the possibility of mass manufacture. We believe that this Special Issue will provide an overview of recent exciting developments in the field of photonic quantum technologies, serving to keep researchers up-to-date with the latest progress and spurring on new concepts in this field.
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)
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 sensing leverages the properties of quantum systems-such as energy quantization, superposition, and entanglement -to achieve sensitive measurements.[1] Quantum sensors can be based on various platforms, such as photons, cold atoms, solid-state spin qubits, and superconducting circuits, for different applications.Over the last decade, quantum sensing has not only opened new avenues for precision measurement in various scientific domains [2,3] but also made remarkable breakthroughs in biomedical, navigation, energy, and other applications.[4-6] To enhance the benefits of quantum sensing, it is crucial to address challenges related to materials [7] and system engineering [8] to improve sensitivity, reliability, and real-time monitoring.Current research efforts span a diverse range of scientific and technological advancements to address these issues and enable new applications.The Special Issue "Quantum Sensing," edited by Tongcang Li, Renbao Liu, and Chong Zu, features 2 review articles and 13 original articles, reporting the latest advancements in the field.This