@qml.qnode(qubit_device_2_wires, interface='tf')
def qf(x):
    qml.RX(x, wires=[0])
    qml.CNOT(wires=[0, 1])
    return (qml.expval(qml.PauliZ(0)), qml.expval(qml.PauliZ(1)), qml.expval(qml.PauliX(0)))
@qml.qnode(qubit_device_2_wires, interface='tf')
def qf(x):
    qml.RX(x, wires=[0])
    qml.CNOT(wires=[0, 1])
    return (qml.expval(qml.PauliZ(0)), qml.expval(qml.PauliZ(1)), qml.expval(qml.PauliX(0)))