We consider the implications for the practical usefulness of a quantum enhanced radar system in the scenario where it is able to outperform any classical counterpart. In this context, we analyze the system from two perspectives, in the frequency range from microwaves to terahertz. On the one hand, we discuss the theoretical implications of a quantum radar system, and on the other hand, we consider technologies for realizing an experimental proof of concept. Our main conclusion is that, while realizable experimentally, useful application of microwave quantum radar protocols to any conventional setting is unrealistic because of fundamental restrictions on power levels.
We consider the implications for the practical usefulness of a quantum enhanced radar system in the scenario where it is able to outperform any classical counterpart. In this context, we analyze the system from two perspectives, in the frequency range from microwaves to terahertz. On the one hand, we discuss the theoretical implications of a quantum radar system, and on the other hand, we consider technologies for realizing an experimental proof of concept. Our main conclusion is that, while realizable experimentally, useful application of microwave quantum radar protocols to any conventional setting is unrealistic because of fundamental restrictions on power levels.
It has been recognized for over half a century that quantum mechanics defines the ultimate limits for sensing devices, and products of that recognition are now on the horizon of practical implementation. One of the most promising of those products is quantum radar, which offers a capability to significantly improve the tradeoff between energy and detection sensitivity compared to classical alternatives. We provide a back-of-the-envelope and implementation-agnostic analysis to glimpse the kinds of expected improvement that a quantum radar could provide for applications of interest. Our analysis relies on relatively simplistic models that are only intended to facilitate an intuitive grasp of quantum-versus-classical distinctions. Such analyses of course cannot lead to definitive conclusions, but we believe they provide evidence that in some contexts quantum radar can be expected to offer realizable practical advantages over classical alternatives. We conclude with a discussion of theoretical and practical obstacles and a high-level summary of what can be said about the present status of quantum radar.
This work, written for engineers or managers with no special knowledge of quantum mechanics, nor deep experience in radar, aims to help the scientific, industrial, and governmental community to better understand the basic limitations of proposed microwave quantum radar (QR) technologies and systems. Detection and ranging capabilities for QR are critically discussed and a comparison with its closest classical radar (CR), i.e., the noise radar (NR), is presented. In particular, it is investigated whether a future fielded and operating QR system might really outperform an “equivalent” classical radar, or not. The main result of this work, coherently with the recent literature, is that the maximum range of a QR for typical aircraft targets is intrinsically limited to less than one km, and in most cases to some tens of meters. Detailed computations show that the detection performance of all the proposed QR types are orders of magnitude below the ones of any much simpler and cheaper equivalent “classical” radar set, in particular of the noise radar type. These limitations do not apply to very-short-range microwave applications, such as microwave tomography and radar monitoring of heart and breathing activity of people (where other figures, such as cost, size, weight, and power, shall be taken into account). Moreover, quantum sensing at much higher frequencies (optical and beyond) is not considered here.
This paper provides a detailed exploration of quantum radar technology, focusing on the generation, measurement, and theoretical analysis of quantum-correlated signals in both optical and microwave domains. We examine the mechanisms behind producing entangled signals and their application to improve radar sensitivity and accuracy in noisy environments. A review of key studies is presented, with emphasis on their experimental setups and the limitations that define the potential of quantum radar. By aggregating data on object detection range and analyzing global research trends through visualizations, including a bar chart and a world map, we illustrate the growing interest and research efforts in this domain. Our findings highlight the significant advancements and remaining challenges in developing practical quantum radar systems, as well as the worldwide collaboration driving progress in this cutting-edge field.
Quantum illumination (QI) and quantum radar have emerged as potentially groundbreaking technologies, leveraging the principles of quantum mechanics to revolutionise the field of remote sensing and target detection. The protocol, particularly in the context of quantum radar, has been subject to a great deal of aspirational conjecture as well as criticism with respect to its realistic potential. In this review, we present a broad overview of the field of quantum target detection focusing on QI and its potential as an underlying scheme for a quantum radar operating at microwave frequencies. We provide context for the field by considering its historical development and fundamental principles. Our aim is to provide a balanced discussion on the state of theoretical and experimental progress towards realising a working QI-based quantum radar, and draw conclusions about its current outlook and future directions.
Quantum radar is an emerging technique, currently at the experimental stage, that promises to disrupt the well-established field of conventional radar. Recent progress shows that it is possible to generate and use entangled pairs of microwave photons for detection purposes and to obtain an advantage over a classical radar. In this work, we study the currently experimentally feasible type of quantum correlation radar. To this end, we compare different radar architectures, quantum and classical, by analyzing their detection performances by means of the receiver operating characteristic (ROC), the minimum error probability as well as the Chernoff bound. The underlying system models are based on quantum mechanical formulations as well as conventional signal theory. Where it is appropriate and necessary to facilitate our analysis, we apply the central limit theorem to establish the Gaussianity of the observable quantities. A conceptual analogy between the quantum and classic points-of-view is drawn and supported by results showing the asymptotic behavior of the ROC curves of both physical descriptions depending on the power levels of signal and noise. We come to exact and comprehensible conclusions on the current state of quantum radar in comparison to classic radar with a detailed mapping of the radar operating regime (measurement time, signal-to-noise ratio, environmental noise level, target object size and distance) in which a quantum advantage is attainable.
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.