Focusing on the problem of vulnerable anti-deception and weak anti-jamming ability in classical pseudorandom code correlation ranging, we present a navigation ranging scheme with true random entangled microwave signals. One path of the entangled microwave signals uses for transmitting signal and another path of the signals preserves at locality. Firstly, the target that possesses the function of quantum repeater receives transmitting signal and forwards it to the locality. Then, correlation detection is implemented between the forwarded signal and the local delayed signal. Finally, the target distance can be calculated by delay measurement. We analyze the ranging precision and anti-deception ability. Results indicate that the scheme not only is superior to classical code correlation ranging precision, but also has very strong anti-multipath ability and anti-multipath interference ability, which will enhance the security of the navigation ranging system. Our investigation has significant application prospects.
Focusing on the problem of vulnerable anti-deception and weak anti-jamming ability in classical pseudorandom code correlation ranging, we present a navigation ranging scheme with true random entangled microwave signals. One path of the entangled microwave signals uses for transmitting signal and another path of the signals preserves at locality. Firstly, the target that possesses the function of quantum repeater receives transmitting signal and forwards it to the locality. Then, correlation detection is implemented between the forwarded signal and the local delayed signal. Finally, the target distance can be calculated by delay measurement. We analyze the ranging precision and anti-deception ability. Results indicate that the scheme not only is superior to classical code correlation ranging precision, but also has very strong anti-multipath ability and anti-multipath interference ability, which will enhance the security of the navigation ranging system. Our investigation has significant application prospects.
A quantum ranging scheme based on dual-path entangled microwaves and coherent detection is proposed to avoid the difficulties of low security, limited precision in traditional radio navigation ranging schemes, being sensitive to multipath effect and the poor performance of existing quantum ranging schemes in current navigation systems. Based on the characteristic that orthogonal quadrature of dual-path entangled microwaves has the largest cross-correlation when the two signals are synchronized, coherent detection is used to get the reference electromagnetic information and calculate the time delay. Based on the principle of pseudo code acquisition and tracking of satellite navigation receiver, a synchronization scheme of time delay is designed, which can acquire the accurate distance ranging. Simulated analysis is implemented in precision and anti- interference, which provide theoretical support for application of dual-path entangled microwaves and a new type of quantum navigation position technology.
There are the common problems of limited precision, low anti-interference ability and poor signal detection performance in the classical radio navigation angle measurement systems. To solve these problems, we present a radio navigation angle measurement method realized by entangled microwave signals. Entangled microwave signals are transmitted to free-space and the quadrature components of the signals are measured in the receiving end. When delaying transmitting signals in continuous real time, the correlated baseline generated by the correlation peak of entangled microwave signals will scan back and forth with high-speed. A receiver situated in the scanning areas could measure the contiguous interval of signals. According to the mathematical relation, the azimuth of the receiver relative to centerline could be derived. Imagining applying it to the landing process of aircraft, we design the implementation scheme and devices. With the quantum space-time correlation and no-clone characteristics, there are superior precision, anti-multipath interference ability and signal detection performance for entangled microwave signals. Our research will serve as a new way for radio navigation angle measurement systems.
Microwave is widely used in present navigation system. It works well, yet it faces precision limit and other challenges. Quantum entanglement has been applied in various fields and resulted in quite remarkable improvements, especially in precision performance. Hence, we attempt to apply quantum entanglement to enhance merits of navigation system performed in microwave regime. This paper introduces principles of microwave-optical entanglement prepared by electro-opto-mechanical converters in detail. Meanwhile, a navigation ranging scheme exploiting this type of entanglement is proposed. The performance of the scheme is analyzed, and factors influencing entanglement feature and ranging feature are discussed. It shows that the ranging scheme has achieved quite precise results with help of microwave-optical entanglement, and it may be regarded as a promising candidate of new navigation ranging scheme.
Quantum entanglement possesses important applications in quantum computation, quantum communication, and quantum precision measurement. It is also an important method to improve the performance of quantum radar and quantum radio navigation. However, the penetration of light wave is poor due to the high frequency, which leads to detecting limitations in bad weather. In this context, quantum entanglement in the microwave domain has been extensively studied, and it is hopeful to overcome the above-mentioned defects in quantum optics. Although the entangled microwave preparation of continuous variable is achievable at present, there exist still some problems such as poor entanglement performance, low entanglement efficiency, complex signal processing and control, which restrict the development of entangled microwave sources. In order to improve the entanglement performance in microwave domain, a squeezing-angle locking scheme based on single photon counting is proposed. First, two Josephson parametric amplifiers (JPAs) are driven respectively by two pump signals to generate two single-mode squeezed states which are uncorrelated to each other. Next, the squeezing angle difference between the two single-mode squeezed states is adjusted to 180°, and then the two signals are mixed in a superconducting 180° hybrid ring coupler for two entangled microwave outputs. The outputs are single photon detected, and the results are sent to the data processor for solution. The squeezing angle difference between the input single-mode squeezed microwaves is estimated by Bayesian criterion and compared with the target value to calculate the error. Finally, the squeezing angle correction information is fed back into the JPA pump to control the squeezing angle of the single-mode squeezed microwave of the JPA output as well as the relative squeezing angle to reach the target value. Thus, the dual-path entangled microwave with the optimal entanglement performance is output. Comparing with the existing entangled microwave preparation schemes, a single photon counter is utilized in the scheme of this paper, which leads to a detection efficiency of 90%. In addition, the Bayesian criterion is used to estimate the output result, and the theoretical precision reaches the quantum Cramer-Rao lower bound. Meanwhile, the introduced noise level and operation difficulty are reduced, which greatly improves the property of dual-path entangled microwave preparation.
We discuss the relationship between the photon frequency used to produce a continuous variable entangled microwave signal and the signal frequency used for its measurement. We analyze the bandwidth of the continuous variable entangled microwave signal and characterize quantum fluctuations using a quantum sideband representation. The quantum fluctuations of entangled microwave signal follow a true random distribution that is similar to noise. And entangled information is reflected by quantum fluctuations. We conclude that the frequency of generated photons corresponds to the center frequency obtained after performing a Fourier transform on the measured signal, whereas the bandwidth of entangled microwave signal is infinite. Due to the high precision of the measurement from its ultra-wideband behavior, as well as the security afforded by the true randomness and non-localized quantum correlation, these entangled microwaves show significant advantages and potential application value in various fields.
Microwave is widely used in present navigation system. It works well, yet it faces precision limit and other challenges. Quantum entanglement has been applied in various fields and resulted in quite remarkable improvement, especially in precision performance, as it can break quantum noise limit. Hence, we attempt to apply quantum entanglement to enhance merits of navigation system performed in microwave regime. This paper introduces principles of quantum microwave entanglement prepared by electro-opto-mechanical converters in detail, which is also adopted by quantum illumination. Meanwhile, a navigation scheme enhanced by quantum microwave entanglement is proposed. The working principles of the scheme, especially those of location, range finding and direction finding, are analyzed in detail. Besides, we compare navigation scheme of quantum microwave entanglement with present navigation scheme. It shows that navigation merits have been enhanced by quantum microwave entanglement, and it may be regarded as a candidate of new navigation method.