Radar is, broadly speaking, the standard way to recognize and identify incoming objects. Aircraft and ships usually broadcast a signal that identifies them anyway, but even in the absence of that signal, you still want to ensure that you accurately identify passing aircraft—and not by the wreckage they leave after you have shot them down.
This is also critical because the approaching aircraft could broadcast a signature that makes it look innocent when, in fact, it isn’t. This form of sophisticated jamming would be very difficult to detect using a standard radar system. When you add the magic of quantum, however, life suddenly becomes a lot harder for the jammer.
via ars technica
