Electromagnetic waves with polarization modulation are widely utilized in Radar and Lidar, depending on classical mechanics and Shannon information theory. In this paper, a quantum detection system using polarized photons has been studied on theory and experiments based on the laws of quantum electrodynamics. We give emphasis on the limits: standard quantum limit(SQL) and quantum limit (QL) for target detection. Two sets photons of orthogonal 653nm linearly polarized beams: 0°,90°,45° and 135° transmit to the target,and detect the scattered photons 5.7 meters away. Transmitter and Receiver synchronize their clocks to suppress the noise by the time filtering.For some targets, our system can achieve utterly confidential target detection in theory.
Electromagnetic waves with polarization modulation are widely utilized in Radar and Lidar, depending on classical mechanics and Shannon information theory. In this paper, a quantum detection system using polarized photons has been studied on theory and experiments based on the laws of quantum electrodynamics. We give emphasis on the limits: standard quantum limit(SQL) and quantum limit (QL) for target detection. Two sets photons of orthogonal 653nm linearly polarized beams: 0°,90°,45° and 135° transmit to the target,and detect the scattered photons 5.7 meters away. Transmitter and Receiver synchronize their clocks to suppress the noise by the time filtering.For some targets, our system can achieve utterly confidential target detection in theory.
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.
The goal of optical target detection is to identify the presence or absence of a target object by using light or photons as the transmitter. This technique offers significant advantages, such as high resolution and precise directionality, and plays a key role in applications like LiDAR. One of the critical performance metrics in optical target detection is noise resilience─specifically, the system’s ability to distinguish reflected signals from crosstalk or jamming sources with similar optical properties. Traditionally, this challenge has been addressed through classical information processing or standard optical filtering methods. However, a new approach to improving noise resilience has recently captured the attention of numerous researchers: harnessing the unique properties of quantum light sources. These sources offer performance enhancements that are challenging or even impossible to achieve with conventional coherent optical sources. In this perspective, we examine the performance and limitations of this emerging method, including challenges related to receiver complexity and power scaling. We also explore potential strategies to overcome these limitations, highlighting the practical advantages these approaches could offer.
Quantum light detection and ranging (LiDAR) utilizes quantum entanglement and correlation to improve precision, noise resilience and covertness of target detection. Despite recent advances, the development of a quantum LiDAR system that simultaneously achieves high precision and a large measurement range remains challenging. Here, we demonstrate a quantum amplitude-modulated continuous wave LiDAR with micrometer precision achievable via increased acquisition time and meter-scale measurement range. In our demonstration, the signal photons directly illuminate the target, while the idler photons are non-locally modulated with a high-frequency cosine wave and never interact with the target. By leveraging the non-local modulation and the quantum correlation, the target detection is achieved with a precision of 0.64 ± 0.06 mm within one second over a measurement range of 2-8 m. As the acquisition time is up to 500 s, the system achieves a precision of 29 ±4μm. Furthermore, our system realizes a 50 times precision improvement over the classical single-photon scheme in a background noise 37 dB stronger than the returned probe photons. With these advantages, our method will open venues for the development of high-precision, long-range, and noise-resilient target detection.
Quantum Lidar is a future technology that can mean different things to different people. To some it means detection and identification of classical-type lidar signals reflected from an illuminated target at or near the single photon level. This is facilitated by advances in semiconductor detector technology that allow highly efficient photocounting. To others it is more stringent, requiring exploitation of covertness associated with being essentially undetectable by the target in a thermal background, whilst allowing the lidar operator to filter her own signal from this noise. Again there is nothing specifically quantum about this. Any source that mimics of the energy rate per bandwidth seen by the illuminated object in the direction of the source can appear covert. In order to exploit quantum optics one can use inherent correlations, whether entangled or otherwise between light beams. Simple correlated optical beams can do this in two ways, perhaps by storing one beam as a reference and later performing correlated detection with the return signal in a phase sensitive manner. This is the “gold standard” for quantum lidar, but will be difficult outside of laboratory situations. In microscopy such phase control might be possible, or perhaps in the radio or microwave region for a quantum radar. Less challenging is a scenario in which an immediate local measurement of one beam conditions the beam sent to the target, allowing the return signal to be sifted from noise more easily. Here we will consider such a simple system, providing a range equation for a basic quantum lidar if it is to be operated covertly or openly. Open operation allows increased quantum signal brightness but also provides a quantum advantage, unspoofability – the lidar operator can in principle recognise their own return signal. We will also provide an analysis of quantum lidar detection based on quantum hypothesis testing and use this to perform Monte Carlo simulation of both target detections and false positive avoidance in a noisy background. The theory will be applied to experimental data.
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.
Quantum radar represents a promising advancement over classical radar systems by exploiting quantum mechanical phenomena such as entanglement and quantum measurement to overcome fundamental detection limitations. This paper reviews the evolution of radar technology from conventional radar frequency systems to quantum radar architectures, with emphasis on sensitivity enhancement and detection of RF-stealth targets for military defense applications. Classical radar parameters such as radar range, transmitted power and cross section are revisited and extended to their quantum analogues. The role of entangled single photon sources in improving detection performance under high noise and jamming environments is discussed. Context of microwave quantum radar is reviewed along with photonic implementations. This paper further highlights the importance of quantum measurement theory, including system-apparatus entanglement, density matrix formalism and wave function collapse in extracting information from quantum radar systems. Although significant experimental challenges remain, recent advances indicate strong potential for future development of quantum radar in next generation defense and surveillance systems.