Error returning expval with qiskit device

PennyLane Help
1

Hi!
I’m trying to use qiskit’s Aer simulator in my Pennyalne program but I get an error when te circuit tries to return an expected value:

‘RY’ object has no attribute ‘return_type’

Here is a simple example:

def circuit1():
    qml.RY(np.pi/4, wires=0)
    return qml.expval(qml.PauliZ(wires=0))

dev1 = qml.device("qiskit.aer", wires=1)
node = qml.QNode(circuit1, dev1)

fig,ax=qml.draw_mpl(node,expansion_strategy="device", decimals=1)()

print(node())

descarga

Thank you in advance!

2

Hi @psansebastian, welcome to the Forum!

I’m running your circuit on a notebook Xanadu Cloud and I get no errors. Could you please post the output of qml.about()? I’m guessing that you might be using an old version of PennyLane. You can use python -m pip install pennylane --upgrade to make sure you’re using the latest version.

Please let me know if this solves your issue!

3

Thank you for replying! Seems that updating Pennylane fixed it!

4

I’m glad this solved your issue @psansebastian!

Enjoy using PennyLane :grinning: