QC: PennyLane

[garncarz]

A new attempt to use QC. This time hopefully even on a real (IBM?) device.

[garncarz]

🤔 So far it doesn't work (using a default.qubit device). For formula $\displaystyle \left(x \vee \neg y\right) \wedge \left(y \vee \neg z\right) \wedge \left(x \vee y \vee z\right)$, it samples {'x': False, 'y': False, 'z': True} which doesn't satisfy it.

[Copilot]

Pull Request Overview

This PR introduces a new approach to quantum circuit creation using PennyLane, aiming to run experiments on a real quantum device. The key changes include:

• Insertion of a new markdown cell that documents the transition to a PennyLane-based approach.
• Addition of multiple code cells to build and execute a quantum circuit based on a Boolean formula, including clause conversion and QAOA circuit construction.
• Integration of simulation devices for analytic and sampling evaluations of the cost Hamiltonian.

Comments suppressed due to low confidence (2)

quantum_computing.ipynb:905

• Consider adding an inline comment to explain the expected structure of 'params', ensuring future readers understand that each layer in the QAOA circuit expects a pair of parameters (gamma and beta).

    "            gamma, beta = params[layer]\n",

quantum_computing.ipynb:906

• It would be helpful to document why '1' is used as the number of time steps in ApproxTimeEvolution, clarifying its intended role in the QAOA circuit.

    "            qml.templates.ApproxTimeEvolution(cost_h, gamma, 1)\n",

[Copilot]

Adding a brief comment to explain the use of the '@' operator for combining projectors may improve readability and aid maintainability.

[garncarz]

💡 Solution for statement = (x | y | z) & (x | ~y | ~z) can be found quite quickly, but it cannot solve statement = (x | y | z) & (y).

[garncarz]

PennyLane-Qiskit plugin creates a session even for the most simple circuits, like this taken from docs:

dev_real_test = qml.device('qiskit.remote', wires=5, backend=backend, shots=10)

@qml.qnode(dev_real_test)
def circuit_real_test(x, y, z):
    qml.RZ(z, wires=[0])
    qml.RY(y, wires=[0])
    qml.RX(x, wires=[0])
    qml.CNOT(wires=[0, 1])
    return qml.expval(qml.PauliZ(wires=1))

circuit_real_test(0.2, 0.1, 0.3)

But IBM doesn't allow free accounts to use sessions. It seems it's been already fixed in PennyLaneAI/pennylane-qiskit#632, but it's still not released and the actual master branch produces (probably an unrelated) error ModuleNotFoundError: No module named 'pennylane.exceptions', so I guess I'll need to wait for a new version.