fix stateprep's normalize (#12988) (#12992)

(cherry picked from commit 5963027)

Co-authored-by: Julien Gacon <jules.gacon@gmail.com>
Co-authored-by: Elena Peña Tapia <epenatap@gmail.com>

qiskit/circuit/library/data_preparation/state_preparation.py

@@ -173,7 +173,7 @@ def _define_synthesis_isom(self):
         q = QuantumRegister(self.num_qubits, "q")
         initialize_circuit = QuantumCircuit(q, name="init_def")
 
-        isom = Isometry(self._params_arg, 0, 0)
+        isom = Isometry(self.params, 0, 0)
         initialize_circuit.append(isom, q[:])
 
         # invert the circuit to create the desired vector from zero (assuming

releasenotes/notes/fix-stateprep-normalize-a8057c339ba619bd.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Fixed a bug in :class:`.StatePreparation` where the ``normalize`` 
+    argument was ignored for input arrays.
+    Fixed `#12984 <https://github.com/Qiskit/qiskit/issues/12984>`__.

test/python/circuit/library/test_state_preparation.py

@@ -113,6 +113,16 @@ def test_repeats(self):
         qc.append(StatePreparation("01").repeat(2), [0, 1])
         self.assertEqual(qc.decompose().count_ops()["state_preparation"], 2)
 
+    def test_normalize(self):
+        """Test the normalization.
+
+        Regression test of #12984.
+        """
+        qc = QuantumCircuit(1)
+        qc.compose(StatePreparation([1, 1], normalize=True), range(1), inplace=True)
+
+        self.assertTrue(Statevector(qc).equiv(np.array([1, 1]) / np.sqrt(2)))
+
 
 if __name__ == "__main__":
     unittest.main()