Specifically, I can't get the correct result using QAOA,A total of 6 qubits were used in this work,this is part of my code using VQE and QAOA localsim = BasicAer.get_backend('qasm_simulator')

optimizer = SPSA(max_trials=500)
ansatz = TwoLocal(rotation_blocks='ry', entanglement_blocks='cz')
vqe = VQE(op, ansatz, optimizer = optimizer)
results1 = vqe.run(localsim)


from qiskit import QuantumCircuit
optimizer = COBYLA(maxiter = 100)
depth = 10
initial = QuantumCircuit(nbr_qubits)
qaoa = QAOA(operator=op, optimizer=optimizer, p = depth,initial_state = initial, quantum_instance=localsim)
results2 = qaoa.run() 

I tried changing depth and optimizer type but it didn't work,The following two pictures are the results of VQE and QAOA respectively enter image description here

enter image description here

Is it because I'm using QAOA incorrectly?

  • $\begingroup$ What was your operator? $\endgroup$
    – KAJ226
    May 29 at 18:56
  • $\begingroup$ op is an ising hamiltonian $\endgroup$
    – Zachary
    May 30 at 4:39

1 Answer 1


I recommend use the new released version, but you can still plot out iteration with graph and compare them, see what happen. choose of optimizer, depth, max iteration will effect the result. reference: https://learn.qiskit.org/course/ch-applications/simulating-molecules-using-vqe


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