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Great comment. Circuits are particularly unhelpful in describing quantum algorithms because they usually indicate a fixed problem size, and they do not provide

Great comment. Circuits are particularly unhelpful in describing quantum algorithms because they usually indicate a fixed problem size, and they do not provide an insight into entanglement, one of the fundamental “resources” of QC. We need new representations and much better abstractions to get away from the low-level thinking we are currently promoting.

throwaway37585 8y ago
> [Quantum circuits] do not provide an insight into entanglement What do you mean? Entanglement occurs whenever the state of a system cannot be factored into a product of the states of its components. Quantum circuits can definitely do that. Just take a qubit, apply the Hadamard gate to it, then CNOT it with a second qubit to get an entangled Bell state. You can see it in action here: http://demonstrations.wolfram.com/GeneratingEntangledQubits/ http://demonstrations.wolfram.com/GeneratingEntangledQubits/. Quantum circuits are also used to describe all kinds of quantum algorithms (quantum Fourier transform, Grover’s algorithm, quantum teleportation, etc).
- antpls 8y ago
  I'm not sure about the actual intent of the grand-parent, but I think it was referring to insight that a larger audience can understand. I have a CS degree, and I don't know what is "Hadamard", "Bell state", etc. Also your link doesn't load on Firefox Mobile Android, so it didn't help :-) Proposing a Python library about Quantum Computing is an attempt at explaining mechanisms to a larger audience (surely it is not an easy task) Edit : the link finally loaded on another tab while writing the comment, but you have to pay for a license of Wolf.A. to run it, I guess. That can't be arguably considered "accessible" knowledge.
- randomsearch 8y ago
  I mean, they do not illustrate when qubits have become entangled. You can't see that. I'm sure we can do better.
  - throwaway37585 8y ago
    I’m not sure what you mean by “illustrate when qubits have become entangled”. Can you explain?
    - randomsearch 8y ago
      Entanglement is fundamental to QC, right? So in order to be a useful visualisation of an algorithm, a pictorial representation like a circuit should give some intuition to aid understanding such as: which qubits can potentially be entangled at a given stage in the circuit, etc.
      - throwaway37585 8y ago
        Why is this (or the demo I linked to earlier) not a satisfactory representation? https://qph.fs.quoracdn.net/main-qimg-1ab704621d3c845630ab6fdc6d1b6259 https://qph.fs.quoracdn.net/main-qimg-1ab704621d3c845630ab6f....

throwaway37585 8y ago

> [Quantum circuits] do not provide an insight into entanglement What do you mean? Entanglement occurs whenever the state of a system cannot be factored into a product of the states of its components. Quantum circuits can definitely do that. Just take a qubit, apply the Hadamard gate to it, then CNOT it with a second qubit to get an entangled Bell state. You can see it in action here: http://demonstrations.wolfram.com/GeneratingEntangledQubits/ http://demonstrations.wolfram.com/GeneratingEntangledQubits/. Quantum circuits are also used to describe all kinds of quantum algorithms (quantum Fourier transform, Grover’s algorithm, quantum teleportation, etc).

antpls 8y ago
I'm not sure about the actual intent of the grand-parent, but I think it was referring to insight that a larger audience can understand. I have a CS degree, and I don't know what is "Hadamard", "Bell state", etc. Also your link doesn't load on Firefox Mobile Android, so it didn't help :-) Proposing a Python library about Quantum Computing is an attempt at explaining mechanisms to a larger audience (surely it is not an easy task) Edit : the link finally loaded on another tab while writing the comment, but you have to pay for a license of Wolf.A. to run it, I guess. That can't be arguably considered "accessible" knowledge.
randomsearch 8y ago
I mean, they do not illustrate when qubits have become entangled. You can't see that. I'm sure we can do better.
- throwaway37585 8y ago
  I’m not sure what you mean by “illustrate when qubits have become entangled”. Can you explain?
  - randomsearch 8y ago
    Entanglement is fundamental to QC, right? So in order to be a useful visualisation of an algorithm, a pictorial representation like a circuit should give some intuition to aid understanding such as: which qubits can potentially be entangled at a given stage in the circuit, etc.
    - throwaway37585 8y ago
      Why is this (or the demo I linked to earlier) not a satisfactory representation? https://qph.fs.quoracdn.net/main-qimg-1ab704621d3c845630ab6fdc6d1b6259 https://qph.fs.quoracdn.net/main-qimg-1ab704621d3c845630ab6f....