I've started learning quantum computing using 'Learn quantum computation using qiskit', and I've stumbled upon what I think is a bug in the code in chapter 1.3: Representing Qubit States when I reached the part and run the code:

qc = QuantumCircuit(1) 
initial_state = [0,1]   
qc.initialize(initial_state, 0)

It returned 'Attribute Error' Saying that 'Initialize' object has no attribute 'label'

  • $\begingroup$ Have you been able to solve this? The above solution results in the following error: ``` QiskitError: 'Initialize parameter vector has 2 elements, therefore expects 1 qubits. However, 0 were provided. ``` $\endgroup$
    – Dunsin
    Jul 7, 2020 at 20:40

1 Answer 1


This is a known bug in Qiskit (https://github.com/Qiskit/qiskit-terra/issues/4439).

As a workaround, you can create an initialize gate and add the missing label using:

from qiskit.extensions import Initialize

qc = QuantumCircuit(1)
initial_state = [0,1]

init_gate = Initialize(initial_state) # Create a new initialize gate
init_gate.label = "init"    # Add a label to avoid the bug

qc.append(init_gate, 0)     # Perform the gate on the 0th qubit
qc.draw()    # Draw the circuit (to complete your code block)

Hope this helps!


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