@qml.qnode(qubit_device_1_wire, interface='tf')
def qf(x):
    qml.Displacement(0.5, 0, wires=[0])
    return qml.expval(qml.X(0))
@qml.qnode(qubit_device_1_wire, interface='tf')
def qf(x):
    qml.Displacement(0.5, 0, wires=[0])
    return qml.expval(qml.X(0))