Microwaves exhibit superior performance in free-space transmission compared to optical waves, primarily due to their ability to penetrate fog and experience lower losses in the Earth's atmosphere. Based on microwave-optical entanglement prepared by nano-cavity electro-opto-mechanic converters, we propose a scheme of a quantum positioning system using the distance-based positioning method. Principles of microwave-optical entanglement preparation and our QPS scheme are introduced in detail. The entanglement feature, system stability and positioning feature of the scheme are analyzed after simulations. Furthermore, we delve into the impact of key parameters, such as transmissivity and photon conversion efficiency, on positioning. Notably, the entanglement degrees for both microwave-optic entanglement at the transmitter and optic-optic entanglement at the receiver surpass one, affirming the efficiency of the scheme in preparing and maintaining entanglement. When transmissivity in beam-splitter models of both ground stations equals 0.5, our scheme achieves a minimal positioning error of 6.4×10-7m2 under ideal conditions. Additionally, we map out traces of a plane through continuous positioning using our scheme. These results demonstrate the theoretical efficiency and robustness of our proposed approach.
Microwaves exhibit superior performance in free-space transmission compared to optical waves, primarily due to their ability to penetrate fog and experience lower losses in the Earth's atmosphere. Based on microwave-optical entanglement prepared by nano-cavity electro-opto-mechanic converters, we propose a scheme of a quantum positioning system using the distance-based positioning method. Principles of microwave-optical entanglement preparation and our QPS scheme are introduced in detail. The entanglement feature, system stability and positioning feature of the scheme are analyzed after simulations. Furthermore, we delve into the impact of key parameters, such as transmissivity and photon conversion efficiency, on positioning. Notably, the entanglement degrees for both microwave-optic entanglement at the transmitter and optic-optic entanglement at the receiver surpass one, affirming the efficiency of the scheme in preparing and maintaining entanglement. When transmissivity in beam-splitter models of both ground stations equals 0.5, our scheme achieves a minimal positioning error of 6.4×10-7m2 under ideal conditions. Additionally, we map out traces of a plane through continuous positioning using our scheme. These results demonstrate the theoretical efficiency and robustness of our proposed approach.
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.
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.
The cavity electro-opto-mechanical converter serves as a meticulously designed platform where hybrid entanglement, including microwave-optical entanglement, can be efficiently prepared. Leveraging microwave-optical entanglement, we propose a quantum synchronization protocol in this paper. This protocol utilizes the second-order coherence function of entanglement signals to determine the propagation time interval and time offset between two parties. Our results demonstrate that the entanglement feature is well-preserved throughout the entire process. Despite the transformation from microwave photodetection to convenient optical photodetection, the transmission superiority of microwaves in free-space is preserved. Under experimentally accessible parameter settings, we achieve a high synchronization precision of Δ τ =±2.704ps. It is theoretically proven that our quantum synchronization protocol holds promise as a viable candidate for future navigation synchronization systems.
Quantum state transfer between microwave and optical frequencies is essential for connecting superconducting quantum circuits to optical systems and extending microwave quantum networks over long distances. However, establishing such a quantum interface is extremely challenging because the standard direct quantum transduction requires both high coupling efficiency and small added noise. We propose an entanglement-based scheme-generating microwave-optical entanglement and using it to transfer quantum states via quantum teleportation-which can bypass the stringent requirements in direct quantum transduction and is robust against loss errors. In addition, we propose and analyze a counterintuitive design-suppress the added noise by placing the device at a higher temperature environment-which can improve both the device quality factor and power handling capability. We systematically analyze the generation and verification of entangled microwave-optical-photon pairs. The parameter for entanglement verification favors the regime of cooperativity mismatch and can tolerate certain thermal noises. Our scheme is feasible given the latest advances on electro-optomechanics, and can be generalized to various physical systems.
Based on the characteristics of superposition, entanglement, non-locality and non-clonality of quantum mechanics, quantum information science can break through the physical limits of classical information and open up a new information processing function different from classical electromagnetic application methods. Due to the advantages of high-energy single photon in practical applications, the research and application of optical quantum information technology dominates the development of current quantum information technology. However, the free-space transmission of light waves is greatly affected by weather conditions and atmospheric particles. Comparing with other wave bands, classical microwave signal shows good penetration ability when transmitting in free space. By introducing quantum mechanics, microwave signal also exhibits non-classical merits. As quantum microwave signal inherits both classical transmission performance and quantum non-classical features, it can be utilized as a significant signal source for diverse applications in microwave domain, such as quantum communication, quantum navigation and quantum radar, which are based on quantum technologies in large scale and dynamic free space transmission. There are three main experimental platforms on which quantum microwave is studied and produced. They are cavity quantum electrodynamics(C-QED) system, circuit quantum electrodynamics(c-QED) system, and cavity electro-opto-mechanical(EOM) system, involving with several nonlinear effects such as Kerr effect, Casimir effect, three-wave mixing, etc. In this paper, the setups of these platforms and the preparation principles are introduced. Meanwhile, the preparation principles and methods of microwave single photon, entangled microwave photons, squeezed microwave fields and entangled microwave fields are summarized and analyzed in detail from three aspects. The present status of experimental progress in the relevant fields are summarized and listed as well. Besides, key problems in the application of quantum navigation in free space utilizing quantum microwave are probed. Among them, the most pressing ones are preparation ability, decoherence in transmission and detection of entangled quantum microwave signals, which are also discussed and analyzed in this paper. Finally, we look forward to the future development of quantum microwave technology. It mainly consists of manufacturing microwave detectors with high efficiency, designing thermal photon filters, and developing suitable antennas. We hope that this study can provide useful reference for scholars who are engaged in or interested in research related to quantum microwave technologies.
We theoretically investigate entanglement in a hybrid quantum system comprising two optical cavities coupled to a shared microwave cavity via optomechanical interactions. Our results demonstrate that increasing the microwave input power and frequency in the allowed range enhances entanglement between the microwave–optical and optical–optical modes. We also show by change frequency of the one optical cavity in the communication domain that we still have entanglement. This ability to generate robust microwave–optical photon entanglement shows promise for various quantum technologies. Optical photons could enable secure quantum communication in optical fibers, while microwave photons allow transmission to satellites. Overall, this hybrid cavity optomechanical system offers prospects as an efficient source of entangled photon pairs, vital for implementing long-distance quantum communication networks.