Design of a quantum radar system with sustainable entanglement

This study mainly focuses on the sustainability of the entanglement in quantum radar working with different types of converters, either electro-opto-mechanical or optoelectronic converters, using full quantum theory at which the priority is to preserve the entanglement. The quantum radar is introduced as a quantum standoff detection system applying microwave photons the same as a classical radar. Quantum radar designed in this dissertation obeys the quantum illumination protocol. Accordingly, the device uses microwave entangled photons to improve detection and enhance identification strongly. From the quantum mechanical point of view, entanglement arises since two quantum particles, such as photons, are produced to interact with each other, and their properties are non-classically connected to each other. The shared properties between the entangled particles are independent of their inter-distance. Unfortunately, the entanglement behavior is so unstable, and more importantly, it is a crucial task to produce and preserve that for a long time. Additionally, the noise can easily affect the entangled states to cause a fast decaying. With knowledge of the crucial points mentioned, this study aimed to preserve the entangled states at each stage of the quantum radar operations, including I. Using a typical converter to create the entanglement between microwave and optical photons, II. Intensifying the entangled microwave photons (if it is necessary), III. Intensified photons propagation to the atmosphere (attenuation medium), IV. Photon scattering from the target. At each stage, the medium parameters can critically kill the entangled states. This Ph.D. dissertation specifically emphasizes the entanglement behavior of a quantum radar system with two different converters (electro-opto-mechanical and optoelectronics converters) as a basic substrate to generate the entangled photons. The converters mentioned will be designed to operate at L-band (microwave cavity resonate at 1.5 GHz) and S-band (microwave cavity resonate at 2.7 GHz), respectively. Thus, we will try to analyze the entanglement between retained photons with the returned photons as the main task of the thesis. The steps of the design of the quantum radar system are as follows: I. Design of the converter to generate entanglement between microwave and optical photons; in this dissertation, we specifically focus on designing the suitable converter to generate sustainable entangled photons to introduce a quantum radar system with high quality. In this step, the trade-off between critical quantities of the converters will be determined. II. Design of the intensifying medium (amplifier in the classic sense) to amplify the entangled photons; This stage plays a primary role in the classical radar since the large range detection is emphasized. III. Modeling the propagation channel as a lossy medium and study the contributed effects on the entangled modes IV. Modeling the entangled photons reflected from the target and target's parameters effect on their entanglement behavior V. Calculation of the RCS via the quantum approach; in this step, we show that the "dipole approximation method" is not a complete method to analyze the RCS.