Think of the quantum state as another measurement to make on the incoming signals. The receiver already measures many characteristics of incoming waves, like fr

Think of the quantum state as another measurement to make on the incoming signals. The receiver already measures many characteristics of incoming waves, like frequency and amplitude, and now it has yet another measurement that can be helpful. It's helpful specifically because they kept a reference wave with the same quantum state. With more data you can get higher fidelity which means you can perhaps see further or see the same distance with less power.