How to output the unitary matrix for a given quantum circuit using pennylane?

PennyLane Help
1

The problem is described in the title. I am trying to obtain a unitary matrix for a specific quantum circuit using pennylane, but I can’t find the available qml. function to get it. Thanks for the help!

2

Hi @cyrie_wang! If you are using the latest GitHub version of PennyLane, installable using

pip install git+https://github.com/PennyLaneAI/pennylane.git#egg=pennylane

then you can access the new qml.transforms.get_unitary_matrix() function:

def circuit(theta):
    qml.RX(theta, wires=1)
    qml.PauliZ(wires=0)

We can use get_unitary_matrix() to generate a new function that returns the unitary matrix corresponding to the function circuit:

>>> get_matrix = get_unitary_matrix(circuit)
>>> theta = np.pi/4
>>> get_matrix(theta)
4 Likes
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wonderful! thank you so much.

4

Hi All,

I just wanted to give a quick update on this topic as it is still well referenced in search engines, and I spent some time trying to find the answer myself.
Since Release 0.23.0 (see release notes) qml.transforms.get_unitary_matrix has been deprecated and the new function to call is qml.matrix you can find the doc here

2 Likes
5

Thank you so much for posting this here @alicewithoutbob!