Question from a computer scientist (not a physicist). Imagine two nodes on a quantum network. Alice sends Bob a qubit in some state of superposition over a quantum channel. Is Bob able to sense that he's received a qubit without measuring it? If so, how?
If you are talking about the idea that the quantum state is encoded on a physical system (perhaps an atom), and that system can be sent from Alice to Bob, then yes, you can detect the presence of the atom without measuring the state of the atom.
To make the point, I'm going to go a bit crazy. I'm not claiming this is exactly a physical scenario.... Imagine Alice has a single superconducting qubit in her lab. This needs a whole bunch of machinery to keep it cold. She can prepare this qubit in any way she wants. To send it to Bob, she has to package up essentially the whole lab (and power supply). Bob will undoubtedly know when the shipping container has arrived, but the lab will still be there, working properly, preserving the state of the qubit.
Bob can't know in any sense that Alice has sent a message, until and unless Bob receives a classical message from Alice confirming that she has sent a qubit.
Even for the sake of argument, let's suppose he somehow knew that Alice has sent a qubit, then arises two scenarios - one, Bob knew it instantly and second, Bob knows only after the time it takes for a light ray to reach from Alice to Bob.
Clearly the first scenario is against the principles of Special relativity, therefore it is not possible. And the second scenario, Bob still has to know what kind of measurements he has to do to get useful information out of it. Therefore if you think hard, you will realise that your question is a redundant one!