Quantum computing with superconducting qubits Demo

Demos
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Use this topic for questions related to the PennyLane Demo on Quantum computing with superconducting qubits.

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Hi - Thanks for the excellent article.
I have a couple of related questions.

  1. If a transmon is used to implement a Pauli-X gate, and the end user wants to send |0> as the input to the gate, how is this implemented?
    Is there a circuitry that reads the specified input and uses a pi-pulse to set the qubit state to |1>?
  2. If the quantum circuit consists of 2 gates, how is the output of the first gate “fed” as input to the second gate?
    Thanks
    I look forward to your reply
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Hi @qage , welcome to the Forum!

  1. The different hardware providers have processes for initializing the qubits in a specific state. I don’t know what the state of the art is for this, but some methods involve resetting the qubit based on the previous measurement, or suppressing excitations by using an auxiliary qubit.
    Applying a Pauli-X gate applies a pi-pulse independently of the current state of the qubit. So you don’t read the state of the qubit, you simply apply the gate. If the qubit is in state \vert 0 \rangle you end up with the state \vert 1 \rangle and viceversa.
  2. You don’t really talk about inputs in this case. You talk about having a qubit in a specific state and then applying a series of gates on such qubit. It’s the equivalent of following instructions on a treasure map. You have a starting point and then receive instructions such as “move 3m north” then “move 1m east”. The state would be your current location at each point in time, and the gates would be telling you how much to move in what direction at each step.

I think you will greatly enjoy the PennyLane Codebook. It will give you some important insights to understand quantum computing better. In particular the learning path on Foundations of Quantum Computing can be key to learning some of the concepts I mentioned.

I hope you enjoy the Codebook! And check out the Codebook category here in the Forum if you have any questions.

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Hi Catalina - Thank you for the quick response.
I will take a look at the Codebook and the learning material.

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