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pythonquantum-computingqiskit

qbit collapse before Quantum Teleportation

I have been tweaking with quantum teleportation in python qiskit. One extra thing that I have done in the following diagram is the measurement of q330 at the very beggining.

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I am doing this because I wanted to see if the measurement is always same for q330 and q332. But that is not possible later part because q330 gets modified.

One alternative way is to introduce a q333 and get it entangled with q330 and measure q333 later along with q332.

My question: I am a bit doubtful that my current implementation is wrong because I am collapsing q330 before the teleportation. That's not what you do teleportation for, right? You keep it's wave property and collapse it later on when needed. I want some comments on my doubt. Than you :)

Solution

  • Your intuition about what you did is correct, a measure on the first qubit has no place here.
    The "correct" way to see if the teleportation works, since here you know the quantum state you want to send, is to do many shots of your circuit to get lots of measures of the final qubits, and then see if the count probabilities match the initial state you sent. On a simulator without any noise, it should work perfectly, and on a machine you would expect some errors due to the noise.

    By the way, introducing this q33_3 in order to copy the first qubit in it to verify if they are the same is not possible due to the no-cloning theorem.

    Also, on your circuit, you forgot a Hadamard gate at the beginning of your circuit, on q33_1, right before the CNOT gate. Without the H gate, you don't create the entangled Bell state crucial to the protocol so your circuit won't work the way it is.

    If you have any other question please feel free to ask ! Also know that there exists a Stack community especially for quantum computing here if you have any question in the future https://quantumcomputing.stackexchange.com :)