Radar in the quantum limit

Deep space tracking radars, such as the Arecibo radar, have Terawatt class EIRP, and are the scale of a small village. As such it seems surprising that one would ask whether their performance is dictated by quantum theory. However in this talk we show that it is, due to the very large losses in link budget. In this talk we discuss the quantum limits of radar performance for deep space tracking and other radars. A radar is said to be a quantum radar if at the detector level we have insufficient RF target photon density to invoke classical physics by means of the Gaussian central limit theorem. We discuss the performance modeling in this regime and in particular look at how quantum theory informs the dish verses array trade.