Aiming at the problem that the classical target detection method is not suitable for the quantum, this paper proposes a new entangled quantum detection method based on the Constant False Alarm Rate (CFAR) model. According to the principle of quantum detection, we adopt a quantum model to quantify the continuous laser energy into a cumulative number of photons to analyze signal and noise characteristics, and select the coincidence threshold in quantum detection. Experimental results show that the proposed method can realize the CFAR function of quantum detection model under different noise conditions.
Aiming at the problem that the classical target detection method is not suitable for the quantum, this paper proposes a new entangled quantum detection method based on the Constant False Alarm Rate (CFAR) model. According to the principle of quantum detection, we adopt a quantum model to quantify the continuous laser energy into a cumulative number of photons to analyze signal and noise characteristics, and select the coincidence threshold in quantum detection. Experimental results show that the proposed method can realize the CFAR function of quantum detection model under different noise conditions.
Entangled state quantum detection is a new technology that combines quantum mechanics with information science, and is used in the field of target detection. It has the potential to break through traditional detection technologies in terms of sensitivity and anti-interference ability. In the field of radar detection, constant false alarm rate is a technology with important significance and application value. However, there is no research on the method of the constant false alarm rate in the entangled state quantum detection system. Aiming at this problem, in this paper a method of constant false alarm rate for the entangled state quantum detection system is proposed. In the proposed method the system's real-time estimation of noise is adopted, and the detection threshold is adjusted adaptively, so that the entangled state quantum detection system always maintains a constant false alarm rate. The simulation results show that the proposed method of constant false alarm rate is correct and effective, and can realize the function of the constant false alarm rate of the entangled state quantum detection system. The proposed method effectively improves the flexibility and adaptability of the quantum detection system, and provides a solid theoretical foundation for the practical application of entangled state quantum detection technology.
As one of the state-of-the-art technologies currently being studied in the field of target positioning, the entangled light quantum-based passive target positioning method uses quantum entangled states to detect and localize the target, thus providing highly-accurate and anti-interference positioning services. The conventional methods seldom consider the problem that maybe a pseudo-target is detected when there is actually no target due to the interference of particles, scatterers, and noise photons during light quantum transmission. To address this problem, this paper proposes a new passive target positioning method on uncertain detection path based on entangled light quantum. Specifically, first of all, by converting the continuous light energy into the discrete photon number, the photon return rate is used to calculate the number of arrival photons based on the counting characteristics of the single photon detector. Second, the detection probabilities of signal, idler, and noise photons are calculated to obtain the coincidence probability at the receiver. Third, according to the coincidence count value of the entangled light time pulse sequence, the Constant False Alarm Rate (CFAR) detection model is established, and the corresponding detection threshold is adaptively adjusted with the change of the background noise to achieve highly-sensitive target detection. Finally, the relative error for each light source is considered to select the optimal light sources with the smallest relative distance errors for target positioning. In addition, the results show that the detection probability of the proposed method is over 95% with the false alarm probability 0.05, the positioning error is centimeter-level, and the confidence probability within 2.60 cm can reach 92%.
In lossy and noisy environments, quantum-enhanced target detection based on temporal quantum correlation encounters low signal-to-noise ratio (SNR), resulting in poor detection performance. To address these challenges, we propose a multi-channel temporal correlation scheme. In this scheme, signal photons from multiple independent entangled sources illuminate the target and arrive at the same detector. Coincidences are obtained by correlation measurements of the entangled photons on one signal path and different reference paths. We then propose a weighted average processing method for fusing the coincidences to obtain higher SNR. The relationship between the SNR and the number of sources is analyzed for different background noise levels. It is shown that the SNR increases as the number of sources increases, but eventually approaches a limit. Experimental results verify the correction of our theoretical analysis.
In this paper, an explicit expression for the maximum detection range of an entangled quantum two-mode squeezed (QTMS) radar, in which a two-mode squeezed vacuum state of microwave electromagnetic fields is used, have been derived by considering both the quantum properties of the entangled microwave fields and radar parameters. By comparing this equation with that of traditional radars, we showed that one can though a QTMS radar as a traditional radar with a reduced threshold signal-to-noise ratio. By discussing the current limitations, it has been shown that the critical parameter to have both simultaneous quantum advantage and substantial radar range is increasing the bandwidth of the generated output signal in the quantum entangled source. It has been shown that by considering the current feasible system parameters, it is possible to implement a QTMS radar with maximum detection range up to the order of 2km, which is suitable for recognizing small unmanned aerial vehicles in urban distances. Moreover, based on the false alarm rate, we introduce two classes of early alarm and track QTMS radars. The present approach can be generalized to other quantum radars with different types of quantum sources like electro-opto-mechanical sources, and also may shed new light on investigating the quantum radar system toward practical applications. Finally, we have discussed the potential outlooks to improve and develop the quantum entangled radar systems to be practical from the engineering point of view.
Quantum illumination makes use of the strong correlation between entangled photons, making it possible to detect targets that break through physical limits. The Gaussian entangled state is a continuous variable entangled state with a high number of Hilbert spatial modes, which is currently a viable alternative to quantum lighting. In order to explore the target detection ability of Gaussian entangled state, this paper starts from the Gaussian entanglement model of Lloyd, establishes the target detection error probability boundary model under Gaussian entangled quantum illumination, and explores the optimal detection condition of Gaussian entangled state based on the detection signal-to-noise ratio and the number of measurements. The results show that when the Gaussian entangled state is optimal for the coherent state, the number of measurements is inversely proportional to the signal-to-noise ratio. Under the same error probability, the difference between the detection distances of the two states is determined by the atmospheric attenuation coefficient. The smaller the attenuation coefficient is, the smaller the attenuation coefficient is, the difference is greater.
Quantum radar based on the mechanism of quantum physics and the quantum information is a new sensing technology that was developed to solve technology bottleneck of classic radar. Especially, The Quantum illumination based on entanglement light beam could overcome noise and information loss. In this paper, the principle of quantum radar is introduced in detail, and the quantum illumination radar scheme using entangled photons is discussed. Then, target detection method based on entangled photons is given, and simulation results are showed. Finally, it is demonstrated by experiments that the performance of entangled photon detection system is superior to non-entangled photon detection system in a noisy and lossy environment, and the targets appear to look bigger when looked with low photon number.