One wire with multi-observables

PennyLane Help
2

Hey @qhc and welcome to the forum!

Hmm, could you post a fully running code example that reproduces your error? And do you have the latest PL version installed?

For example, running this code with PL 0.15.1 works with no problems:

import pennylane as qml

dev = qml.device("default.qubit", wires=4)

@qml.qnode(dev)
def circuit():
    qml.Hadamard(wires=0)
    return qml.expval(qml.Identity(0)), qml.expval(qml.Identity(0))

print(circuit()) # [1., 1.]