Deep space tracking radars, such as the Arecibo radar, have Terawatt class EIRP, and are the scale of a small village. As such it seems surprising that one would ask whether their performance is dictated by quantum theory. However in this talk we show that it is, due to the very large losses in link budget. In this talk we discuss the quantum limits of radar performance for deep space tracking and other radars. A radar is said to be a quantum radar if at the detector level we have insufficient RF target photon density to invoke classical physics by means of the Gaussian central limit theorem. We discuss the performance modeling in this regime and in particular look at how quantum theory informs the dish verses array trade.
Deep space tracking radars, such as the Arecibo radar, have Terawatt class EIRP, and are the scale of a small village. As such it seems surprising that one would ask whether their performance is dictated by quantum theory. However in this talk we show that it is, due to the very large losses in link budget. In this talk we discuss the quantum limits of radar performance for deep space tracking and other radars. A radar is said to be a quantum radar if at the detector level we have insufficient RF target photon density to invoke classical physics by means of the Gaussian central limit theorem. We discuss the performance modeling in this regime and in particular look at how quantum theory informs the dish verses array trade.
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.
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.
Quantum Radar! Check out what Wikipedia says about it: it might render stealth aircraft obsolete. Watch YouTube videos that purport to explain all about it. Read press reports in which China claims it field tested one in 2016. But is there any fire underneath all that smoke? This talk will answer that question by telling the story of “quantum illumination”, from its beginnings through recent theoretical and experimental results. Quantum illumination is the only quantum radar concept that has been proven, theoretically, to outperform all classical radars of the same transmitted energy in detecting a weakly-reflecting target that is embedded in strong background noise. It uses a source of quadrature-entangled signal and idler beams to gain its target-detection performance improvement despite loss and noise that destroys the entanglement. A realistic assessment of that improvement's utility, however, shows that its value is severely limited. Nevertheless, the fact that entanglement can be of value on an entanglement-breaking channel — the meta-lesson of the quantum illumination story — should spur continued research on quantum radar.
This paper presents the advantages and limitations of a quantum radar system. The use of entangled photons to interrogate a region of space where a target is supposed to be, gives a lower probability of error than using a classical signal. This is possible because of the extra information that the quantum entanglement property can give us. This information helps us to distinguish between the signal reflected from the target and the background noise. Finally, through simulations, it is shown that the actual advantage of the quantum radar is the ability to detect a target in a high-losses and high-noise environment using a weak signal.
At the current state of the scientific discourse on quantum radar, the best understood and experimentally feasible types of implementation are based on two-mode-squeezed-vacuum photon states and aimed at the task of target detection. The operating environment, in which an advantage over classical radar may be attainable, is thereby limited to the extreme regimes of very low signal-to-noise ratios and high thermal noise levels as well as confining the required hardware at mK temperatures. In this work, we approach the open question of how to optimally operate a potential quantum radar system. To this end, we define the optimal operation by means of the detection advantage against classical radar as well as the efficient usage of the resource measurement time. We show that there is a trade-off between time-efficiency and out-performance of classical radar and specify the conditions for such an operation. Building on this aspect, we investigate the concept of the fair classical comparison to facilitate the understanding of its relation to quantum radar.
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.