Entanglement Sustainability Improvement Using Optoelectronic Converter in Quantum Radar (Interferometric Object-Sensing)

In this study, the main focus is laid on the design of an optoelectronic converter as a part of the quantum radar to enhance the entanglement between retained and returned modes at high temperatures. The electro-opto-mechanical converter has been widely studied, and the results showed that the operation at high temperature is so crucial to generate and preserve the entanglement between modes. The main problem arises because the mechanical part operating at a low frequency leads to a large number of thermally excited photons, and eventually, the entanglement between modes becomes lost. To solve the problem, we replace the mechanical part with the optoelectronic components. The optical cavity is coupled to the microwave cavity in the newly designed system through a Varactor diode excited by a photodetector. As the main goal, to improve the entanglement sustainability, the effect of the coupling factor of the microwave cavity to photodetector is investigated. The results show that the mentioned factor creates some degrees of freedom to enhance the entanglement at high temperatures compared to the electro-opto-mechanical converter. At some specific values of the coupling factor, the retained and returned fields remained completely entangled up to 5.5 K and partially entangled around 50 K.