def statevector_from_ansatz(ansatz,
var_parameters,
n_qubits,
n_electrons,
init_state_qasm=None):
assert n_electrons < n_qubits
qasm = ['']
qasm.append(QasmUtils.qasm_header(n_qubits))
# initial state
if init_state_qasm is None:
qasm.append(QasmUtils.hf_state(n_electrons))
else:
qasm.append(init_state_qasm)
ansatz_qasm = QiskitSimBackend.qasm_from_ansatz(ansatz, var_parameters)
qasm += ansatz_qasm
# Get a circuit of SWAP gates to reverse the order of qubits. This is required in order the statevector to
# match the reversed order of qubits used by openfermion when obtaining the Hamiltonian Matrix.
qasm.append(QasmUtils.reverse_qubits_qasm(n_qubits))
qasm = ''.join(qasm)
statevector = QiskitSimBackend.statevector_from_qasm(qasm)
# print(qasm)
return statevector
def test_hf_states(self):
n_qubits = 5
n_electrons = 3
qasm = QasmUtils.qasm_header(n_qubits)
qasm += QasmUtils.hf_state(n_electrons)
qasm += QasmUtils.reverse_qubits_qasm(n_qubits)
qiskit_statevector = QiskitSimBackend.statevector_from_qasm(qasm)
sparse_statevector = scipy.sparse.csr_matrix(
openfermion.utils.jw_hartree_fock_state(n_electrons, n_qubits))
array_statevector = numpy.array(sparse_statevector.todense())[0]
for i in range(len(qiskit_statevector)):
self.assertEqual(qiskit_statevector[i], array_statevector[i])