Error when set_state_simple() used

[hovnatan]

When I run the following code with MPI: mpirun -np 2

circuit = qiskit.circuit.library.QuantumVolume(n_qubits, depth=5, seed=1001)
ket = np.zeros((2**n_qubits, 1))
ket[2] = 1
circuit.set_state_simple(ket)
circuit.measure_all()
circuit = transpile(circuit, simulator)
simulator = StatevectorSimulator()
job = simulator.run(circuit, shots=1024)

I get the following error: cusvaer.backends.ubackendext.RuntimeError: stateSize does not match with the state vector size

If I omit circuit.set_state_simple(ket) the simulation works. Can you please help?

[ymagchi]

Hi @hovnatan,

For the distributed state vector simulation in cusvaer, set_state_simple() sets 1 sub state vector assigned to each process: https://docs.nvidia.com/cuda/cuquantum/latest/appliance/cusvaer.html#set-state-simple-state.
In the above case, the expected state size will be (2**n_qubits) / 2.